Yes I heavily used them (old LSAT tests) and I got a 41, although I think it may have backfired, since I scored much lower on the verbal than I had on any practice tests.
The problem is that the LSAT CR questions are straight to the point and very logical. Basically there's a clear pattern to their logic - there wasn't a single unnecessary word in any of the questions. And if you look at the old paper tests or GMAT Prep when GMAC used to lease the questions from Law Services, it seems that GMAT questions were like that too. But on the actual test the questions were wordy, had no pattern, were illogical, and tried to trip you up with implausible scenarios and convoluted wording rather than actual tough logic questions.
Basically, what ended up happening is that I'd read the question on the GMAT, expect a certain answer based on how the LSAT would answer it....but none of the answers were even close.
Now, the same thing for RC. The LSAT uses harder passages, do doubt about it. They're longer, have more difficult subject matter, etc. However, the questions are much easier and straight to the point. All they're trying to do is to make sure that you can read high-level passages and answer simple questions about them.
The GMAT took a different approach. The passages I got were shorter, easier to read, simpler subject matter. However, they made the questions much harder and tried to trip you up with word games, convoluted language, and other bullshit. Why not just use harder passages and have straightforward questions...like the LSAT?
Sorry this is a lot of text, but from you're previous posts I gathered you're looking to retake the GMAT (as am I), so hopefully this helps.
