I had a Raychart 420 installed before I upgraded recently to their SL72RC (radar/gps combo unit). Overall I was very pleased with the 420.. nice compact unit good display. GI would have kept it if the price I was able to get the new unit for were not so attractive. The 420 got me home every time from offshore. I did not have any problems with the 420 except user caused errors while learning the unit.
I thought overall it was a good value for the money.