If the sex is amazing, I would stick with her! I had a couple of previous long-term arrangements that were great.Hey, a bit late to the party, and haven't read all the posts, but here's my $0.02:
Been in a SA relationship for a few months now. It's my second one - the first was decent but the ppm was pretty high in my mind. The tradeoff was she was young, hot, and the sex was amazing.
The second one has honestly been mind-blowing. We click in most regards, which makes the SB concept more appealing for me than going to an SP.
We are ppm but it's pretty fluid, if we meet more than once a week then it's usually a smaller amount for the second meeting. While it is still transactional, she's never even asked for the money - one time I almost left without leaving it, and I had the feeling she probably wouldn't have said anything.
The only downside is that is feels like it might be trending towards a relationship, which would spell disaster, but so far she's on board with the fact that I'm not leaving my situation.
I had to go through a bunch of conversations on SA before finding each of these, but it wasn't overly taxing for me... for most it was pretty clear right away that it wasn't going to work. What I like about it is that it's upfront in terms of what both sides are looking for, so it's easy to get straight to things like expectations and desires.
Based on what I spend vs what I get in return I'm totally satisfied with the SA relationship. Of course that won't be everybody's experience, but here's hoping it works for you!
My current one has been going for a couple of months and it's just OK. I am thinking about moving on because I would like to recapture the amazing experience from my previous ones.
I have to admit that sorting through the profiles and having coffee is a pain but I may be at that point soon.