I dove sidemount a couple of times on demo dives. While it was neat to suspend myself in any crazy position in the water I continued with DIR back mounted doubles because of the way this system has matured and is standardized.
Do not nullify these advantages by obsessing about your individual solution. Follow the advice others have given you in this thread, throw this thing on your back, and dive.
What does the wise man do with a Porsche? Put some glitzy wheels on it, agonize over the floor mats, or enjoy driving a car that is the benchmark of performance refinement?
The aluminum doubles are great because they are easy to dive and cheap. If you ever do not need them anymore, take them apart und use the bottles for stages.
Most likely that's not going to happen. Even after getting big, honking steel tanks for cave diving that hold about twice as much gas I did not ditch the AL80 doubles. If there is strong flow coming out of a cave, the AL80s and a wetsuit get me just as far as the steel monsters and a drysuit. Never underestimate drag in the water.