I'll offer up my opinion, but if the condom feels right, then use it. If there's slippage, or it's coming off your cock, then don't use it, but apart from that, go with feel. I used Lifestyles for a while, until I realized that a condom isn't supposed to hurt when you put it on and take it off, then switched to magnums. There is minimal bagging around the head when i'm not fully hard, but it is snug along the shaft and doesn't slide or move at all.
Personally, I think the little extra movement in the head feels better - more friction along your cock. Love to hear what anyone else has to say on this.