Great deals, I typically will do a search for F one my domestic routes just to see how it prices out. It can be tricky though. Most of the QUP fares that I have seen have been non-refundable. There are some that are refundable but most of the ones that I have seen have not been. So, if you automatically assume that by selecting first class on the web site will give you a refundable ticket....that could cause a problem. If you purchase them in conjunction with other F segments that are not refundable I believe the QUP segments will prices as refundable also but not sure. It is still an economy fare basis but it automatically puts you in an F seat and gives you the discounted first class booking code A so you get the EQM bonus.
As others mentioned they are great deals and I looke for them on about every domestic flight.