I've used Sound Studio 4 for many years for simple general stereo sound file tasks. It's inexpensive and certainly has many limitations, but it works for me. It's very convenient to split a long file into separate tracks (segments) for mastering a CD. It's easy to do simple cutting and pasting, fades, trimming, normalizing and so on. The developer told me that whenever a 24 bit file is converted to 16 bit, TPDF dither is added with no options. Sample rate conversion is simple, but doesn't look as good as the best on the Infinitewave SRC comparison website, which is odd because I assumed they just use the Apple Core Audio algorithm SRC. Concatenating stereo files is a matter of simple cutting and pasting. I've had no problem joining 2 hour-long files 24/96 but just cut and past -BUT- I discovered I had to leave all soundfile windows open during the process. I couldn't open the 2 files, copy the second half recording, close that window, and paste onto the first half - without crashing.
What it is poor at is using processing plug-ins; multitrack mixing, and tight editing. I use Reaper for that, also inexpensive and works well, much better than Audacity for me. BIAS Peak died and I never got to like it much. Adobe Audition CS5 was pretty good, but had several buggy slow operations that may have improved in CS or CC6. I've never been on the ProTools path.