Compared to HD plus oxidiser (only fair way of comparison), I doubt you'd be able to measure the difference, after all it's a very subjective thing, the performance of one product or another isn't it
I'm using SPM more and more now; I started carrying it on the van to use as a trial whenever I had the opportunity but I've found myself reaching for it more and more as my first choice.
I think I'll still carry both, because sometimes I'll want the HD's strength but without the oxidiser which is included in the mix of SPM.
I think it is a fantastic product. Did a FILTHY job last week- polyester suite and polyprop cut pile carpets - barely needed to spot anything and the result actually amazed me.. and it's not very often my jaw drops open at how clean a carpet comes up.
One thing I've noticed is when you spray it on Vanish patches, they just disappear instantly! This is great in one respect but sometimes you forget where you have to go slower with the wand to rinse the patches more thoroughly. Doesn't seem to be a problem though.
Does have its niggly little problems such as lumpy bits, and it is a very fine powder so on a windy day like today half of it can blow away when you're trying to scoop it into a bucket! But no big deal, I'll take that hit.
One other thing I don't think many are on to yet... for very dirty jobs, use SPM as a rinse agent as well as pre-spray - one wand pass over a filthy traffic lane and it's tickety boo. It is seriously better than the liquid high heat I usually use in my TM. Touch wood doesn't seem to be causing any deposits/clogging problems either which is good.
Only down side to using it as a TM rinse chem is I wouldn't want it on every carpet & suite - I have to swap back and forth between the alkaline SPM and acidic high heat which is a nightmare if I've got high heat already mixed up in the container, got a minger to clean first thing, but then got to do a nice clean cotton suite afterwards. It means either mixing up just enough to do the job which is a pain, or transferring in/out of holding containers during the day. I haven't got the space for two chemical jugs to swap the pipes between.