Do not throw good money after bad. You are already IFR by having the VOR and ILS equipment with your current GPS.
Most of the older IFR GPS units require a CDI and an ACU to be IFR legal in addition to having the database for the approach being flown.
The question to ask about the 155XL is will the spare parts run out before the database is no longer published?
Gary A. Sobek
NC25 RV-6 Flying
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.