I have the 90B in my E. Database updates are available and aren't that expensive. My first choice would be a WAAS capable panel mount, but the reality is with dual ILS on board I just can't justify spending the money on a WAAS capable panel mount right now. My 90B is definitely quirky. The menus are cumbersome and it occasionally flags the RAIM. I can easily replace the unit with a serviceable one for about $1500. The 530W is in my future, but several years down the road. That being said, if I didn't have a gps already in my panel, I would probably be looking for a used 430W/530W or an Avidyne. Once you factor in the installation costs, a slightly more modern WAAS capable panel mount makes a lot of sense.
V/R
Rusty Nance
2719W
M20E