Keep your current reservation.

As CPRich mentions, this gets into the fuzzy area (and should only be done within Coupon Connection & with someone who is established) & isn't worth the risk for 20K points.

Second, a Cat 8 property would require the same amount of points whether you made the ressie or the other person did, unless he made the ressie by chance for the same nights you wanted & did so before it jumped up in category. That doesn't seem likely.

Third, I don't think you can transfer 140K points at one time.

Fourth, what's in it for the other person? Is he just trying to get 140K points from you?

You're Gold. You'll have access to the exec lounge regardless.

Again, for 20,000 points my recommendation is to just keep your current reservation.

PS - Enjoy your stay at the Marriott!

Cheers.