Well, I used Peak off and on from within Logic for destructive editing, but there were issues with Peak regarding updating files once they were saved, since Peak 4.x at least.
I've tried DSP-Quattro and AudioFIle Engineering's Wave Editor also. I have settled on IcedAudio's AudioFinder.
With AudioFinder as my external editor, I can open the file from within Logic and pick and choose which ever editor I need to use for the job.
From within AudioFinder I can access Peak, DSP-Quattro, Wave Editor, Sample Manager, Loop Editor, Melodyne, iZotope RX, etc. Very cool. Very handy.
Once the file is saved, it ends up back in Logic. Peak still has the saving issue, but I believe the rest have been behaving.
I have Presonus Studio One Pro, purchased on a half-off sale that I have used to assemble CDs with. It's pretty idiot proof and is laid out nicely, similar to how WaveBurner worked.
Hope this helps.