The Moment is Large, hard to call it "Huge" that would be the T-Mobile Sidekick. The Hero is smaller, but not "tiny".
The Hero has a flashy UI, if you need it, it's great. If not, it's just added fluff.
Moment WILL be getting Android 2.XX the question is when, Hero is on the same road as this, first half of next year is the predicted date. Lotta folks like to over look that Moment and Hero have the same dates predicted for this release.
The coating on the Hero also leads to easier scratching, where as the Moment has a very scratch resistant screen. The oleophobic coating really cuts down on fingerprints, which are wiped off easily. Scratches, on the other hand, do not wipe off.
The Moment is faster than Hero in every aspect pretty much. And gets bogged down rarely, where as Hero can get bogged down easily just switching programs quickly with programs running in the background.
The Moment has a brilliant AMOLED screen, which does have a blueish hue, but it is not so bad that you or anyone else will notice it unless you are really looking for it. The AMOLED screen is really amazing, just hold it next to a phone with a normal screen, like the Hero, and you will see the difference.
I loved the Hero the first few days I had it, than really began disliking it. I have never had a physical keyboard before, so the Hero's virtual keyboard I felt at home with, however after switching to physical on the Moment I will never go back. Just something nice about haveing a real keyboard with nice feedback. And if you want the Hero's keyboard you can get something very similar off the market. You can't do the reverse and get a physical keyboard.
Personally I'd advise AGAINST Hero, at least untill they get quality control under control. There is a major issue with there being a gap between the screen and the keypad. This gap allows dust and other particles to get in under the glass, after only 2 weeks I had a very visible amount of dust under mine. There is no way to get the dust out without disassembling the phone. Just think of longevity of the phone, how bad will the dust be in a year?
Aside from that, the Hero is nice. SenseUI looks great, and adds some really nice widgets. I just can't advise a person to get a product with such a large flaw in it.
This is not to say that Moment is without it's bugs. Read around this forum and you will find them.
I have not heard any news of new Android phones coming to Sprint as of yet.
Also Look here for more info ---->
http://androidforums.com/samsung-moment/10864-hero-vs-moment.html