I'd like to publicly thank Brian, KT6LN, for loaning me his Bird wattmeter. It confirmed that I am getting about 17 watts of power out of my DEMI 2330PATV and, more importantly, there is no reflected power. So I am getting probably about 300W ERP into K6BEN/R. It's actually been working lately, though the video doesn't look amazing, and I'm not completely knocking down the FAA RADAR QRM like some of the stronger uplinks do.
I was also able to use his wattmeter to confirm the output of the 70 cm amplifier on ATSC, though the issue there is that not all of the power coming out of the amp is actually useful signal, if you're not careful.
My experience with ATSC makes me wonder whether part of that 17 watts is out-of-channel crap that isn't contributing anything useful to my receive signal at the repeater. But this is FM TV we're talking about. Even a class C amp should be fine.
I also am not getting a P5 picture back down from the repeater. I'd say it's P4.5 or so. I suppose some of the imperfection I'm seeing is on the downlink side. I am, however, happy to just get in.