Do you really think 2 liters is that much??? What size wing do you use and how many breaths does it take you to inflate it?
Let's explore the opposite direction, just for the kicks. Assuming unlimited funds, and, just for a second, suspending any potential concerns about the negative impact on gear familiarity as a result of changing gear too often, what in your opinion would be the optimal composition of the diver's toolbox, specifically? Separate cold- and warm-water sidemount kits, multiple sets of back-mounted manifolded doubles with wings of varying sizes, a singles setup, a rebreather? More than one rebreather? Independent doubles? Jacket BCD? What would provide incremental benefits, however small, and what would be 100% superfluous?
Shallow recreational diving-single tank backplate/wing, regulator configuration setup like the Dive Rite's Streamlined OW rig, i.e. the left post of a set of doubles.
Other recreational diving-doubles of some sort
sidemount-one mexico style for al80's and balanced rigs, one florida style for others.
rebreather
two DPV's, one long range cave, one light weight boat/backup
Drysuit
Wetsuit-probably 2 for different conditions
This somewhat looks like my gear. I have a plate with singles wing for the weird chance that I dive singles. Hasn't happened in years, but I can do it if I want. I have both kydex and SS plates depending on ballast needs
I have a doubles wing and independent doubles cam bands to put my sidemount tanks in without needing tools. I also have a normal set of doubles, but only take them if I know I will need them. I.e. boat/scientific diving. I disagree that sidemount is the optimal configuration for wreck diving, but that's personal preference. Those that do aren't wrong, just different.
I have two sidemount rigs depending on lift requirements, though the Katana is doing damn near all of my diving right now. At some point in the near future a CCR will be on the way and that will be sidemount due to cave diving, but with no money restriction I would have a Sidekick and Meg15.
I firmly disagree with jacket bc's, they honestly don't have any merits over a backplate and wing for any style of diving. Anyone who disagrees hasn't dove one that fits them properly, or is in a mentality of "comfy" with it and not wanting to change. No problem, but I truly see no scenario when a jacket is advantageous