Incidentally, yesterday I switched out the Fender speaker from my 1992 Fender Princeton 112 Plus (65W solid state fairly cheapish amp I got when quite a bit younger!). I put in one of the Peavey Sheffield 1200 speakers (16ohm, 75W power handling, much MUCH higher efficiency - as I found out...) from my 5150 cab (I'd switched all of these out previously). The amp now has VERY different characteristics than it did before. The cleans are superb, I'm actually surprised how much nicer they are now with the Peavey speaker than the Fender one - glassy and rich instead of cold and sterile. Under distortion, the amp kicks a lot more bass out, and handles the baritone register so much more ably than it did before. Oh and the whole lot is about a million times louder than it used to be! Oops! Can't comfortably get the volume above 0.5/10 in the house now! LOL
Anyway, the moral I wanted to bring out was that changing the speakers can sometimes have very surprising effects, and very dramatic effects at that. Definitely worth experimenting if you have the chance!
Roo