I haven't done coke but I did lots of meph.. and I usually drank not only on the comedown but even when the meph was still working and it worked great for me. It made the high even better and I didn't need to do so much meph to get there.
Seriously don't think it's dangerous, especially beer is a good idea actually to drink after stims, 40% whiskey with no water not so much.. I say if you like beer, don't hesitate, if you don't drink something else, just not too quickly.