I always ask, because I have seen superintendents argue grass vs sand face hard, both ways. I think it may have something to do with sand quality in the area, rainfall, and other factors, so I just go with the flow....or flash.
In general, I agree with Tom. Deeper bunker faces probably equal higher maintenance costs either way. There are mowers than can hang one of their three gang blads over a steep bank, and thus machine mow from the top at nearly full speed. So, any grass face deeper than that probably means some hand mowing. And, maybe even less, depending on the turning radius up top, but many mowers can turn on their own radius.
For some reason (cost) many supers do not like growth retardants, but it would seem to me some use would eventually net enough savings to be worth it. I get Primo or lower cost equals from my friendly supers, and it has always helped me reduce mowings of my front lawn, so I love it!