It's the compression and RPM's that kill the motors. Compression knocks out the bottom end and RPM's are hell on valvetrain components.

I know one local (Midwest) sprint team that is finally freshening their motor this winter after nearly 50 shows. They used some nice lightweight bottom end parts and kept the compression at a reasonable level. This team was never lacking for horsepower to run up front almost every night out.

I would have to believe that a lighter weight crank is easier on the block as the lower reciprocal weight would stress the main webs less.

Another factor to consider with a higher overall weight motor is the crash energy that heavier unit carries. I haven't seen near as many motorplates torn out in a crash since the motors have become lighter.
The motor plates haven't gotten any heavier or stronger in this period.
Less mass = less collision energy.

Just my .03 cents. Inflation hits everything sooner or later.:thumbsdown: