Yes, I'm a huge fan of using LSAT CR and RC questions, and there's a really long, wordy post about it on my blog if you're curious.
https://www.gmatninja.com/2012/11/12/lsa ... rehension/But to save yourself a click (and some unpleasant reading?), here's the short version: the LSAT basically tests the same skills (reading precision and logical precision) as the GMAT CR and RC, and the passages are generally more difficult on the LSAT. For some people, the LSAT materials will be way too hard, but if your reading skills are pretty good, they'll give you a really good workout, and they'll train you to stay focused while you power your way through dense, boring, nuanced, annoying texts.
There are some cosmetic differences between the LSAT and the GMAT, though. The LSAT has a few question types that rarely appear on the GMAT (most notably parallel reasoning), but I think they're still good practice, since the underlying skills needed to handle parallel reasoning questions are basically the same: phenomenally precise reading and careful reasoning.
And best of all, there's an almost limitless supply of retired LSAT questions out there, so you don't really have to worry about running out of material. LSAT passages are longer and the language is pretty brutal, but my hope is that after you do tons of LSAT stuff, the language on GMAT CR and RC won't look quite as difficult.
Enjoy! OK, fine... you won't enjoy them. But I hope they help!