Tina: I've been doing Barre/Pilates mixed with cardio and Yoga and one heavy lifting day for about 3 months now. Before that it was mostly heavy lifting and cardio with some Yoga. I do two days of Barre/Pilates, two cardio days, one heavy lifting, and 2 Yoga. I also do a shorter Yoga practice in the evening if I have time.
I have noticed some definite changes, and really wish I had measured when I started. I had a pair of jeans I bought at the start of the summer that I couldn't even get zipped up without laying down on the bed. And then I couldn't breath anyway. I put them on again last week, and they zipped without any problems. All my pants are fitting MUCH better thru the thighs too. I don't know what it is, but I still have plenty of muscle definition in my upper and lower body.
I have Pure Barre, Squeeze, some Callanetics, and a whole bunch more (I've become addicted). I can handle Cathe's mega-tough lower body work, but Pure Barre has me quivvering like jello!
p.s. I have not noticed any decrease in actual strength either, but that may be because I'm still doing one day a week of heavy lifting.