I have experimented extensively with shorter mash times, and I also BIAB with a very fine (but uneven--corona mill) crush. The only times I have found it necessary to go over 45 minutes is when I'm dealing with low DP and/or low mash temperature. In those cases, the extra 15 minutes is required to get my extract up to normal levels. I use a HLT and dough in and infuse by underletting the mash. It's so easy. It let's me do 2 or 3 rests. It allows me to dough in without overheating the mash at first--so I can get at the fines with beta amylase and produce a very fermentable wort if I want (I often do want). My usual:
English Milds: 30min@158, 5min transition, 10min@162
Bitter,porter,stout: 30min@150, 5min transition, 10min@162
Cream ale, Australian sparkling ale: 45min@148, 5min transition, 10min@162