The G430 has over 10,000 units in service , Garmin has no intent to stop providing support for these , that being said , when Garmin stopped support for the MX20 , they gave a 4000 dollar trade allowance for a new GMX200 , if you push , they will give a 2500 dollar trade for an MX20 against a GMX200.... They did stop support for the GX series, but I don't think they had the number of units out in the fleet , also the GX series was an Apollo product that predates the Garmin name....As far as a GTN upgrade you are looking at a 5000 upgrade over the 430 , GTN = 10,500 G430W = 5500 ..... The 94 is a good legacy unit , the two problems being 1) screens are no longer available, 2) No rs232 output for GPSS ......The 94 is worth about 1500 on the open market , The SL40 about 1100 , I would sit on the 94 and wait for an all in one box for ADSB out.....There will be a 3000.00 all in one box within the next two years..... Trig , and Appareo are in the loop to be certified..... Everybody talks about the 650 being such great tech , the only thing it does that the 430 does not , is touch screen.........P.S. the screen on the 94 will last forever as long as nobody tries to use it like a touch screen......When they push on the screen , that's what kills em....