I'm not even close to being a pro... so take it with a grain of salt.

After i started training with power i can't see myself going back. I've done some road races, TT's, OD and 70.3's with it.

For road racing it was pretty useless for me... maybe if you want to do some break-aways and know your 3-5 minute power it can be helpful... but I had enough trouble hanging on to the pack during the surges

For TT's and tri's it is an amazing tool... feels almost like cheating. If you know your numbers it is a great tool.

But the best part is it well help you with following a solid training schedule. Without a PM i don't think i would ever broke the 40km/hour with a 40k TT. Which might not be much for some of the folks here, but for me it was a huge milestone.

So i rate it a solid 9 out of 10.