I bought D2G years ago and swore by it. I got an invite a while back to "test" a copy of Office Suite Pro and I found the interface much better and the functionality also better. I ended up purchasing it also. I have yet to have it crash on anything (I hope I didn't just jinx myself!!) I can't say that I have any particularly large spreadsheets, but I have some that are decent size and OSP has never choked. D2G is a great product, but I, personally, prefer Office Suite Pro.
BigRedGonzo