I only used fixed on the track (Velodrome), but I love it. I don't really see the attraction on the road, but that's probably just because I love my road bike. I only have the two bikes, and they are both wonderful in their different contexts. I do think that using the track bike, especially on rollers, can be beneficial for skills and pedalling technique, plus higher cadence cycling - my son had to do a 10 mile roller time trial with restricted gearing on his road bike - due to his track cycling he managed to average 138 rpm over the 10 miles (just over 17 minutes).