Do note that my schematics cover only a very small percent of Crate products. In those which I have the lower power GX/GFX models (50W or lower) tend to use only Zener diode-based clipping. They all have two clipping stages with back-to-back Zeners configured to provide asymmetric clipping. Both stages have the FlexWave circuit.
Higher power GX/GFX models (from GX/GFX-65 and up) that have two OD channels (rhythm and lead) use the VBE-multiplier ("rubber diode") based clipping for lower gain sounds of the rhythm channel and add a Zener diode based clipper/extra gain stage before it when the lead channel is activated. In this case, the Zener diode stage usually has symmetric clipping and doesn't utilize the Flexwave circuit.
In all cases all clipping is introduced within two gain stages.
Exceptions naturally exist - even in such large numbers that it's hard to make any universal description. For example, GX-120 uses only Zener-based clipping in two gain stages and has two individual gain controls for the first gain stage. Note that there are also various versions of the models that have slightly different circuitry. For example, I don't know anything about the first revision of GX and GFX amps. Bass (BX), keyboard (KX) and tube amplifiers do not use FlexWave at all - at least not the ones I have schematics to. Taxi series has it in some models, e.g. TX-30 has FlexWave while TX-50 doesn't.
All this, of course, covers only the clipping / gain stage structure of the OD channel. Personally I regard the voicing taking place pre/post clipping as an equally important issue (if not even more important). Again the amps with two OD channels tend to be quite different in this respect than the "simpler" amplifiers.