Fair enough on the 175 comparison being apples to oranges as it does not include charts which is the large data usage. IFD updates however include full Nav/obstacle & charts if you subscribe to them as I currently do. Below are Avidyne's quoted numbers which are consistent with what I see (about 5-6 minutes for full US nav, obstacle and chart data). I agree with you that SA datamanager has improved and is typically trouble free now, although still clunky and not available for MacOS. My surprise was that Slingshot which is supposed to be a big improvement takes over an hour in the plane. That is a far worse tradeoff for me than updating the USB sticks on datamanager on the PC.
From:
https://pilotsupport.avidyne.com/kb/article/562-ifd-database-upload/
Typical upload times are:
Worldwide Obstacles (1.5 MB) – 5 sec
Eastern US Charts (100 MB) – 3min (5xx only)
US Charts (180 MB) – 5 ½ min (5xx only)
Worldwide Charts (430 MB) – 13 min (5xx only)
US Nav Data (8 MB) – 20 sec
Europe Nav Data (10 MB) – 20-30 sec
Australian Nav Data (1.5 MB) – 5 sec
Worldwide Nav Data (15 MB) – 40 sec **See Note Above**
Ok, now I had to think about this a bit more.
I think (please correct me if I'm incorrect here), that the Avidyne products use only vector charts and plates (Jepp sourced?), versus raster image FAA charts and plates. Vector data is more size/storage efficient than raster images, so this would translate into significantly less time to update overall for correlative items (i.e. vector charts would be smaller and take less time to transfer than correlative raster charts).
However, the Garmin 175, the IFD540, and even (I believe) the Avidyne PFDs all use ONLY vector charts (again, please correct me if I'm wrong here); whereas the Garmin PFDs (e.g. G3X G1000, etc.), Garmin portables, such as the Garmin 696/796, and Dynon HDX/Skyview PFDs use, or make available, BOTH vector and raster charts (user selectable).
With Dynon HDX/Skyview, you update the vector data (the NAV data), which the digital charts/moving map are generated from when you update the free Dynon database (which also includes airport and facility data). But Dynon's database does not include approach charts, IFR or VFR nav charts, it includes only the digital data that is used to generate the vector-based nav map. With Dynon, if you desire VFR, IFR charts, that look like the FAA charts (because they are), and Approach Plates that look like the FAA plates (because they are), you subscribe to them through Seattle Avionics and get that geo-referenced raster data onto USB thumb drives and plug them into the Dynon displays (either the database manager or now Slingshot). Because these charts/plates are built from raster images rather than digital or vector data, they are larger and will take longer to update. If all you want or need is the digital nav maps you don't need a Seattle Avionics subscription, nor do you need to spend time updating them.
Similarly, Garmin panel PFD/MFDs (G3X, G1000, etc) and the larger Garmin Portables (696, 796, etc.) have digital/vector NAV data that is used to generate a digital moving map, and you have the option to purchase and use raster image charts and plates as well. I believe on some you also have the option to purchase vector-based plates too.
The Garmin 175 is a navigator that I don't believe has an option for raster charts and plates at all, only digital/vector data. I'm not sure trying to view an approach plate of any type on the smaller screen makes any sense either. Using the Navigator assumes you have some other form of the plate, either on your iPad, your PFD, or in paper form.
And again, with Avidyne products, navigators and PFD/MFDs, I believe you only have vector-based charts and plates, and no option for raster charts and plates. Again, please let me know if I'm incorrect here.
So, if this is all correct, there would be no apples to apples comparison between time updating charts/plates on a Dynon HDX (using Seattle Avionics data) and a Garmin 175 or Avidyne IFD540, because they don't have apples to apples support for nav, charts, and plates. All of these devices have digital/vector nav data that is used to generate digital charts/moving maps, so updating ONLY that data would be a valid time comparison I suppose.
Seperate from this discussion would be a discussion on the value of raster charts/plates vs. vector charts/plates. I would suggest that each has their advantages and disadvantages. To begin with, raster charts and plates look like, and the information they contain are, identical to paper charts/plates many of us grew up on and are comfortable with. They have been optimized over many decades to show the most information they can using color, symbols, line styles and various shading, simply because they had to. Everything you needed for a VFR or IFR flight needed to be there or if not there, easily referenced in the little green AFD books. On our electronic displays, the raster data is usually contained in chunks, and in more than one resolution for each chunk, so the optimal resolution can be displayed for different zoom levels. This avoids really grainy zoomed-in views and losing thin lines altogether when zoomed way out. Vector data on the other hand is used to generate, on the fly, charts and plates at specific zoom levels, so it does not have that resolution issue to contend with. It also has the benefit of being able to "declutter" by not displaying everything it can, at various zoom levels, or by user control. Oftentimes though, it is lacking in other features and information that are available directly on raster charts, requiring you to select and item and then get "Info" on it, or look up that info separately in another way (like radio freqs, runway lengths, available services, ATC freqs, etc.). Other info, like weather conditions, winds, graphical TFR's, and even traffic, can be placed atop either raster or vector maps. Sometimes they are and sometimes they aren't depending on support by the product and available information.