I'm with Hoser that generally the 2-12 or 3-15 or 4-16 scopes of decent quality nail the majority of tac LR matches that we encounter. Read Zak's articles on tac LR -- he's a big proponent of "less is better" for specific reasons (well thought out, imo) but generally shoots exceptional quality glass (S&B, Zeiss/Hen., PremReticle). www.demigodllc.com
I use a PR 3-15 (with the Gen 2 XR reticle). For the Tac LR matches, having some hold over/windage demarks in the reticle are key. Std MilDot, S&B P4F, etc. are all good options.

PDog matches: OK, I will admit that I yearn for some more mag at this match. The 425 yd shots look like titmice at 15x. When I've looked through Hoser's 5-25 S&B, and I dial to the mag that "I like" I'm usually around 17-18x. Is 15x through great glass a handicap on this size target? Too strong of a statement although I often wish I had marginally more mag. I definitely wouldn't want to be dialing the zoom from shot to shot though. Getting the elevation dialed and re-positioning for good technique & wind correction is enough to worry about between shots (for me).

Observation: just because you have some mondo zoom range, doesn't mean you have to use it. I can't imagine wanting/needing to dial past 15x for 100 yd shots. I do the SnipersHide Dot Test (look it up if you don't know it -- great technique drill) adequately at 15x.
And, if you're seeing huge heartbeat effects at any range, there's something in your set up that likely needs to be tweaked.
All, IMHO, of course.