Convenience - Modded Collectors - Dev Ease of use - depends what is being done. I think a golden rule is to have both, just because it seems to resolve any issues.
I use my modded retail RGH slim running RGLoader a lot more than I use my XDK. I'd rather my retail crapped out much quicker than my XDK, especially when its on for hours on end attached to Visual Studio. So another +1 for modded retails! XDK is nice to have though!
agreed, When i have long sessions of forza 4 gaming, id much rather stress my falcon jtag rather than my XNA
For me anyway then it always begs the question of what is the point in owning something that you barely are going to use in fear of it crapping out on you. Or for a lot of people who own an XDK, owning it, and simply using it to play games and nothing else and never utilising its full potential. Slightly off-topic, but does anyone else go through phases of collecting stuff and then eventually get to a point where you just think, why am I doing this? and then sell it all off.
Nah in all honesty if you're dev savvy, an xdk is just as easy to mess with as a Jtag/RGH. Honestly, a Jtag or RGH retail hacked is a like training wheels on a bike. An xdk is the bike without training wheels and fully unlocking the full potential is like riding a flaming unicycle. It all depends on what your comfort and education level is.
Playing beta and retail conversion games. Playing roms with emulators. Diving deeper into basic code. Etcetera. Basically I want to see how far I can push the capabilities.
Basic purposes/some betas/emu's/homebrew, JTAG/RGH is the best. For alpha games and actually programming, XDKs XDK is better but rarer.
A good question to me is what SHOULDN'T I be using my kit for. Just them existing is an issue since both are likely going to die one day. Other than that I use mine mainly for Rez and some footage capturing. I don't use it for much else but my main focus is prototypes of sorts.
Start with JTAG/RGH. Work your way up. A dev kit is a waste of money if someone doesn't know what to do with it...