Horrible. They're great for stage and I have a few different types, but NONE sound like a saxophone should. The reason is simple. The majority of the output of a sax above the G finger position comes from the upper half of the instrument. what comes out the bell is thin and weedy. Get down to maybe E and it's a mix, and from D and below, almost 100% from the bell. The best overall recording position is one that allows the mic to capture the entire instrument. Bell mounts also pick up vibration. Most have rubber as an isolator, a few use a spiders web design like bigger mics. Tenors, in particular clack and clunk and physically mounted ones always have some of this in the output.
On the interface question - I never think of interface and mic as a single purchase. You buy an interface to handle the ins and outs of the system, at a quality level you want to be at. You then select a mic to do what you need. Once you have a good enough interface, you can hear the difference between mics, but at the bottom end, it becomes the quality limiter. If I had a lot of money to spend, I'd point it at the interface. However, once you are at the right quality areas for you - it takes a lot of money to improve it just a little. A $100 product is always outclassed by a $200 one, but a $1000 one is not hugely better, and to then improve on that could be $3000? Mics just all sound different. Money does not guarantee better sound, just different sound in a positive way. If you have a very expensive mic, you can still find an SM57 might suit a song better?