Greg is installing an LSX block into one of his customer's cars. He's a member here (mdickie), so I would guess he knows quite a bit about it. And, of course, Greg should be a fountain of knowledge about it.
Thing I wasn't crazy about is that the LSX is an iron block. So it's going to be heavier than the other LS series blocks. The LSX weighs in at 225 pounds, which is about twice that of a typical LS1 or LS2. How much is too much TO YOU may be a question you need to consider. Possibly not as much as simply adding some of the forced induction options around, so maybe a non issue to many people.
From what I have read, the LSX was designed to hold up with engines pushed 2,000 to 2,500 horsepower. So it's possible that such a block may be overkill for most people who are planning to drop it into a streetable machine.
Here's a few links I found...
http://www.gmhightechperformance.com...ock/specs.html
http://www.supercars.net/PitLane?vie...D=0&tID=110248
http://forums.corvetteforum.com/show...p?p=1561657106
http://www.camarotech.com/engine-LS.html