I've recently made 3 tenors and a soprano completely from sapele, a tenor uke and a guitar from sapele with a mahogany soundboard and a tenor from sapele with a spruce soundboard. I'm happy with the way they all sound.
I use sapele because its readily available here in the UK.
Compared to mahogany its a little heavier and since I use mainly hand tools and do a lot of planing and scraping (no drum/thickness sander), I am aware that sapele is harder than mahogany. On the plus side, I don't think it scratches as easily as mahogany. Whilst a lot of sapele has the ribbon grain associated with veneers on doors/furniture, it can also be very attractive.
Both mahogany and sapele are opened pored timbers. I have finished my instruments in Tru oil without pore filling though on some I've achieved a high gloss finish by repeated wet sanding with Tru oil using the slurry formed to pore fill.
I am happy using sapele: I am a hobby maker not a pro.