If by cut her loose you mean just stop seeing her, then why not? If what you're getting from the SB is of the exact same quality as your ATF at a much lower rate and you'd prefer to save money, then just stop booking appointments with your ATF. That way when things get weird or go south with your SB, as they so often do, or you just get bored with her, you can go back to your ATF without having burned a bridge.  
   
 I would advise not trying to re-negotiate terms with your ATF. No one likes to be told that they are no longer of the same value to someone they've been intimate with, regardless of whether or not that intimacy was transactional. I mean, how would that conversation go?  
   
 "Hey, you've been really good to me and I love spending time with you. You're hot and good in bed. But there's another girl who is also hot and good in bed and she charges for unlimited time what you charge for an hour. Can you do the same or better? Otherwise I won't see you anymore."  
   
 Or what if a provider said to you:  
   
 "Hey, you've been really good to me and I love spending time with you. But my time is starting to be limited and there's another client who is just as good as you but he tips very well and/or leaves before his time is up and lets me keep the full donation. Can you do the same or better? Otherwise I won't see you anymore."  
   
 The appropriate response to both of those questions would be "Go fuck yourself".  
   
 If you don't want to see your provider anymore at the terms you agreed to, then just don't see her anymore. But it shouldn't be her responsibility to lower her standards to compete with another woman.  
   
 As an aside, there are so many intangibles - boundaries not being the least of them - that go into providing that comparing it to sugaring isn't a fair match. Sugaring might work great for some people - it sounds like it does for you - but while it *is* sex work, it is very different from what we do. There's a lot of emotional labor and other unseen, but very much felt, aspects to this work that clients enjoy but don't necessarily notice...which is kind of the point. We make it awesome for you without you ever realizing all of the work that goes into making it so.  
   
 And if you think your friendship with your sugar baby is "actual" - and it very well might be - tell her you've hit a bump financially because of the holidays and you'd like to see her but you can't provide anything for your next couple of meetings. If she's actually your friend, that should be ok, right?  
   
 This young lady might be different, but I just had two friends tell their (now former) SB's that the money faucet was either getting turned off or slowing down and they got told to go to hell and the girls' SA profiles were reactivated and updated in less than 24 hours. One had even told her SD that she was madly in love with him and had been writing him love songs/poems/etc.  
   
 Just some food for thought.