The LMB-3 is a very capable compressor with variable threshold, fully variable ratio from 1:1 (no effect) to Inf:1 (hard limiter) and plenty of control over the make-up gain. It can be used as a clean boost by setting the ratio 1:1. There are no controls for attack or release. My experience with the LMB-3 is that it is a very transparent compressor that brings little coloration to the sound. It does not do the 'squeeze/swell' thing typical of the Dyna/Ross OTA type compressors so if you want that then look elsewhere. The point with a compressor more than any other 'effect' is that recommended settings, esp. threshold, make no sense. We have to use our ears and match the settings to our instrument(s). So if the input is always below the threshold (very low output vintage instruments, for example) there will be no compression regardless of the other settings. Maybe consider a line booster to give your compressor something to work with, or get a comp that has an input level control.
Ultimately, the compressor changes the envelope of the note, so you can get useful interactions with envelope filters and pitch-tracking effects. Placed after a Q-TRON, a comp can tame frequency peaks. But things get really interesting when you place the comp first. You could, for example use it to shape the decay of the filter - flattening the envelope will reduce the filter peak and slow the closing/opening of the filter in sustained notes. Combined with an appropriate sensitivity setting, a low threshold/high ratio might be used to keep the filter completely closed (or open) until you really hit a big note. If you are triggering synths or pitch shifters/octave pedals, then hard compression in front can really help tracking.
I like my LMB-3 - on it's own I don't know it is there until I turn it off (always a sign of a good compressor), but as a feeder/shaper for other things it is magic.