Gravelpit isn't a bad map, but I typically dislike it. It can get some decently long matches going, but if you're on the losing side of a short match... it just tends to feel so crappy (does on any map but losing this one stands out). As for defending A over B it can be done but you're team needs to be alot more steeled then when chosing A over B (and by that I mean making sure snipers, sollys, demos, spys, and ubers don't take out engi placements vital to keeping the point).