I notice a lot of threads lately on reducing the draw weight of favorite bows. Well, we're all getting older, I guess.
I have a couple (including a couple of customs that are very special to me) that I would shoot a lot more (and probably a lot better) if they pulled a little lighter.
I'd like to know if reducing draw weight by 2-8 pounds significantly shortens a bow's lifespan, or otherwise impairs it's durability.
If the limb edges weren't overly rounded initially, and if the belly glass wasn't sanded, then it's possible to take off 2-4# without affecting the bow's shooting characteristics or durability much. Going beyond that requires some fairly heavy limb thinning and/or limb edge rounding. Some folks have reported taking off 5#-10# or more, but that usually also includes narrowing a limb that was pretty wide to begin with. That changes the dynamics of the bow if not its durability.
I wondered this same thing a couple weeks ago. I have been shooting a PSE Impala TD recurve, 60"-50@28" that I picked up in the bargain cave at Cabelas for just over $100. I figured what the heck, if I ruin the limbs I'm not out much. So, I set the table saw fence up to take half a blade width off each side of the limbs. These limbs were about 1-5/8" wide before starting, and came out just under 1-1/2" when cut. I then rounded both sides with 80 grit and then finished with 120. Before the final sanding I checked the poundage with my hand held scale and it lost 5 lbs of draw weight. I haven't checked them after completing the sanding, but it probably didn't change that much. I have been shooting it in the online turny and really notice the reduction in poundage. This was a smooth bow to begin with and now it is even better. I notice nothing as far as hurting the longevity of the limbs, time will tell. Hope this helps!