I like the LA4s on guitars... to me, they sound very much like a VCA type instead of an optical comp. They are good on a lot of things, acoustic and electric guitars, vocals, bass, drums. etc. Anything where you need good sounding compression..
I would try to find a pair of them, so they can be used in a stereo configuration. For any of the UREI stuff to track stereo well, it is most desirable to find units with adjacent serial numbers or at least within 10 numbers apart.. sometimes units produced on different days don't tie together well and won't track stereo accurately.