I’ve been seriously looking at going towards side mount diving. A good shop website to look at is Dive Gear Express. They have lots of great information on sidemount. They sell the appropiate harness BCDs and will even sell completely set up sidemount regulator rigs (two regulators, hoses, gauges, etc). I have also had a conversation with my LDS the other day about side mount and they would be reluctant for people to dive off their boat while wearing, for example two AL80 tanks (difficult to manage that amount of tanks on the boat while others were trying to get their own gear on at the same time). However they would be OK with smaller tanks, for example two AL40s - I had never considered AL40s, but in the end that would equate to the standard AL80 that most LDSs use.
Another reason I’m looking at sidemount is to eventually go and take a self reliance dive course so that I can solo dive.