I love spinning, but am probably biased, I am an instructor (spare time, it's not what I do for a living...).

I agree with others that I did see it improve my endurance and technique considerably when I started spinning (as a student). I noticed a marked improvement and I was also lucky enough to find instructors who rode outdoors (there are plenty that do not) and they were able to use the class for focusing on technique, like pedaling etc. that helped me learn how to focus on that same technique when I got on the road. And altho I have a trainer for my road bike also, the spinner with a routine, esp going to a class, is much more interesting....

Your cadence BTW, 95 ish is a very good cadence, but it depends on your resistance (if you are indoors) or the wind and hill conditions (outdoors). If you are doing 95 with a low resistance factor, you are probably in a sprint and working endurance/cardio (110 is about the max you should go for)...obviously that cadence will go down on a hill (70's) or in a strong wind condition (working on strength). And of course standing on the bike makes a difference. So don't feel bad when your cadence drops, for the right reasons....there are times to do 80 and times to do 100!!

Hope this helps!! Keep spinning....and find the best instructor for you!