It all comes down to the installation cost and the legal requirements for all the extraneous blinkers, switchers, hookups and non-converter equipped CDIs, and signoffs.
I personally find panel mount GPS a false economy, certainly for the VFR flavor. The IFR GPS flavor has to be judged by the individual user and how much they're willing and able to plunk down. Yeah for the money-is-no-object crowd the choice is simple, but for the rest of us mortals, it simply does not make any sense to plunk down 10K+ in installed costs for a system that will see occasional hard-IFR use into the mythical airfield one intends to supposedly fly in and out of in IMC that only has a GPS approach, with no suitable alternate fields in a 1000mile radius with a simple VOR approach, to wait out the weather on for 45 measly minutes
The reality is that for the majority of the peanut gallery that flies in radar controlled environment, who fly single engine pistons whose operators and passengers can't stand much more than the nominal benign IMC in the first place, and with a cursory knowledge of the ATC system, a garmin 1/2/3/4/96 and dual VOR/COMM setup will get you there pretty much the same as the 430w gizmo dude. And I actually prefer the moving display on my 196 versus the 430, go figure. The fact that it's detached from the panel and therefore redundant, and has a cost delta beyond ludicrous when compared to the panel mounts, is just icing on the cake for me.
So in closing I think you should keep the 250XL and use it in combination with the 496. Keep the dozen of thousands for FLYING baby! Now, before the IFR GPS pharisees come and crucify me for stating such blasphemy, consider we use the 496s with WX in the B-52 and it works like a charm, and we're actually actively dodging weather with it at 450+KTAS across the continent, which is a more complicated go/no-go decision than the decision matrix for the median unpressurized altitude GA piston mission profile and the nominal level of actual IMC one would try to fight through on a recreational flight, mind you. Granted, I'm not shooting GPS approaches to an uncontrolled field of 3000 feet length in OVC200 RA+ in the BUFF, my field lengths are 10K and most are surveillance approach capable, but who the hell is anyways !?!?! That is such a statistical outlying and marginal of a percentage of the IFR use for these piston single demographics, it simply does not add up to a cost delta worthwhile the extra flying hours you could burn, versus a portable GPS combo /A or /U setup. Obviously if you're to run with the 300XL and employ it IFR with an illegal setup (such criminals we are....), then the acquisiton cost would be worthwhile. Legal setup though? Nah, just use the VFR GPS and request direct with it every chance you get. Works just as good as filing /G with a terminal GPS.
Happy flying bud.
