With the SL30 you will get both of them. You will need to select the OBS on the SL30 which doesn't cause any problem in daily use and you will be able to display two RMI needles at once on the EFIS, the one in the active NAV frequency on the SL30 and the one on STBY as well.
If you switch your EFIS from NAV to GPS (changing NAV source) your only RMI needle will be the GPS one. You won't be able to mix GPS and NAV.