I had M22/VP100/QS8/Hsu STF-2, upgraded to M60/VP150/QS8/STF-2, then finally a VTF-3R. The M22 + sub is a very good combination. That said I think the M60/VP150 is a worthwhile upgrade, if you have the space and money. The M60 has more presence in the upper bass and lower midrange.
Don't get stuck over analyzing it. Either combination sounds great. If I only had M22s and a sub I'd be very happy. Even with those you are probably more limited by room acoustics and source material quality than by speakers. Yet M60s are sufficiently better to be worth the money and space, if you've got it.
