Power meters are really useful for a few things:
#1 - adding a level of precision to training that heart rate cannot give you. Especially for short intervals, HR responds too slowly.
#2 - benchmarking against others and yourself over time and over varying conditions (flat/hilly, windy/calm, different bikes, etc.).
#3 - learning how to pace yourself - a PM will show you really quickly how much your output varies in a ride, and how you might be "burning matches" where you did not intend to.
There's a reason virtually every pro today trains with power - if you are serious about performance, you can't beat it.
For a leisure cyclist, while you would get something out of a PM, there are probably other places for bigger gains. From what I've seen (and I used to run a high end bike studio, so I've worked with many cyclists) most recreational riders need to:
- get a really good bike fit
- hire a good coach for at least 3-6 months to teach you the basics (including strength training and nutrition)
- invest in better accessories: shoes and bib shorts being most important
One other thought - Strava has a power estimator that might give you a taste of power metering, at least in the post ride analysis, I think it's included in their free service but you might have to pay for the premium to try it out.
Hope this helps!
Thanks for the detailed reply.
Strava power numbers are way off the mark from what i have been told.