I play around quite a bit in my regualr clothes. I don't know that I do any really strenuous training, per se, but maybe a dozen or so rolls on the grass, some touchy-feely-slappy with a friendly partner, so on. I don't find it particularly difficult (moreso than normal training) because of the clothing, but I do think it's different. For instance, I wear my pants rather large, and I have to pull the front up slightly to initially get my knees bent.
The biggest difficulty for me comes when I kneel down for a pin. The shoes pinch my toes, and get uncomfortable after awhile. However, for most of the sliding and walking, it's just fine.