If you get a price request you will be asked to set a BIN price anyway, no reason to wonder whether you should or not.
As for the BIN,
you need to consider whether you want your domain to appear on Afternic's Network or not. If you do then BIN is required.
As for the BIN vs Make Offer in general,
there are way too many threads on that already with various answers and approaches. I strongly suggest you do a search on NP.