S30V needs to be taken further on the stones (to a crisper apex), for stropping to have a more meaningful impact. A sequence that's worked very well for me, is to finish S30V on Fine DMT (600/25µ) --> EF DMT (1200/9µ), followed by either or both of EEF DMT (3µ) and 3µ diamond compound (Dia-Paste). In particular, the EF DMT and the 3µ Dia-Paste produce some BIG changes in final sharpness, and quickly. Prior to trying that sequence, finishing with the EF & 3µ diamond paste (on basswood), I held essentially the same opinion of S30V as you mention; after trying it, my opinion completely changed, and I wondered why I ever thought S30V was difficult in the first place. Really an eye-opener for me.
Any strop substrate that's not very, very firm will hamper or handicap the effectiveness of diamond compound on high-vanadium steels like S30V. The compound performs much better when it can 'dig in it's heels' on a hard substrate, instead of just sinking too deeply into a softer substrate (like leather); that'll give it good footing to cut high-wear steels very cleanly at fine/EF/EEF grit levels. This is why it also helps greatly to take S30V as far as possible on the hones, before going to the strop. AND, using the diamond compound on a firmer substrate like wood (better yet, hardwood) will allow the compound to work more effectively.
The other steels you mentioned aren't nearly as wear-resistant, so they'll respond more easily to stropping than will S30V, even when the apex may not be quite as crisp prior to stropping. Even then, taking it as far as possible on stones will still produce better results. The stropping compound will still work just as aggressively and remove metal, but an incomplete apex will finish up more rounded off as a result, if attempting to 'fix' imperfect or incomplete honing by stropping alone.
David
