Like we all know... just 'cause an Engineer has access to good gear don't mean he's gonna be a good engineer. Likewise... if an engineer knows what he's doin, then you can bet that cat can make "bargain" equipment sound like it's more than it is.
If you've got Spice1 and other folks doin their thing with good results on lower end gear, I suspect it's more your engineering and the artists ability than it is the gear. I haven't heard the Marshall, but regardless what Mic ends up in your Mic Cab... the better your signal chain, the better the sound. With that said, if I'm the one spendin... I'd save up the bread and move up to the next level of mic.