The combo I've built Jonathon goes from clean, through plexi tones to 2203 on steroids. It hasn't quite got as much gain as a SLO, nor is it that compressed, but it could be made to do so (pix to follow SOON).
The REAL problem is that building such an amp takes as much effort as building a 100w version. People just won't pay around £800 for a 10w class A combo, though thats how much it'd have to be to make a 10w hand-wired amp worthwhile (unless you're components are of average quality - I prefer to spend the extra rather than compromise on tone).
I don't think this is true. It all depends on the right marketing (as well as the overall demand and competition for sure).
A Carr 8W Mercury is 2,000GBP, a Cornell Plexi 7 is 750GBP, a Soldano Atomic 16 is ... etc
I think what you cannot do is offer the 10W amp in an MDF combo shell of a solid state Marshall. It must appear worthy, then it can cost.
And surely, if you can get Joe B. to play a stack of 10 of them on a public gig which you get on Youtube, that can help as well :oP