I thought I'd update this a bit.
I bought another two 650ss faucets, and I am pilferring two from my direct keg draw setups for now. I figure they will get more use on the coffin box than they will on those setups, at least for now. Right now the plan is to replace all the faucets, then I can get two more for the direct draw setups.
I hope to replace the four faucets tonight, replacing the shank fitting with the john guest fitting, and putting the bev seal ultra line on.
I've been doing more tests on the single faucet I have installed currently, and it is pretty consistent that if I only draw off a sampler size, it has a lot of foam and is a bit warmer, but it is drinkable. If I pour a whole pint, it has a normal amount of head, though I do currently have it set with increased resistance, so it takes about 15-16 seconds to pour a full pint.
This is definitely going to be an expensive way of saving 2 ounces of beer at a time, but given how much beer I've thrown away, I still think it is worthwhile for me and the effort I put in to making the beer.
I'll be selling the four 525ss faucets to another brewer in the club, which will allow me to get another 2 650ss faucets, and at that point, I'll have changed out half of the faucets on the coffin box.
I'll definitely be doing more testing once these new four are replaced to see how well they work on different beers.
Once concern I have is a note I noticed on one of the online sites selling the 650ss faucets, that they aren't good for highly acidic beverages like cider, wine, or sour beers because some of the 304 stainless that they used was reactive - which really means to me that if it is true, they aren't really using true 304 stainless. I'm actually not that worried, though I may send a note to Perlick for confirmation of that.