The D74A has wider coverage RX wise, plus SSB. I've never used mine for WX satellites, so can't comment on how it would work. It does have a built in TNC. Regardless of it's age, nothing else on the market has all the 74's features in a handheld. I'm keeping mine, I know the menu very well and need an APRS handheld for satellites. The APRS implantation is excellent.
The 52 is just a beast, I don't consider it as competition to the D74A. So far, from what I"ve seen online, what is does it does very well.