tldr: use whatever works best for your setup
The advantage of a 212 is that the 2 speakers are intentionally working together to act as a larger membrane to drive a tuned volume of air that sounds the best. The 112s are tuned to sound as good on their own and may or may not blend together in a way that is equal to the 212
For example I stacked a semi-open 112 with a g12h30 over a oversized 112 with a classic lead 80. The lead 80 cab had extended bass response and the h30 had more treble so I thought the end result would cover both areas. While it sounded big and 'fine' I guess, it didn't result in what I thought. The h30 dominated due to being more efficient and the oversized bass response seemed to be less. I assume due to phase cancellation.
While unlikely, with 112's the speakers could be out of phase (1 pushes forward first vs the other backwards) but you could get some + / - phase issues as they are both pushing different volumes of air due to how they are tuned. So a 212 could sound 'better' as it is designed from the get go to get the best tone out of the 2 speakers. Maybe 2 of the same 112 cabs would work better but sometimes different combinations will surprise you.
Realistically it will work fine and it may be the best solution to your set up. The monitoring issue could be both due to the v30s cutting a little better and the ability to point it at your face. If your typical show doesn't have a pa or monitors and your cabs have to work as both, feedback will probably be THE issue you need to deal with if you're pointing a 112 at ear level and it bleeds into the mic vs the 2x112 or 212 argument.
If you were at the point where monitoring was fine but the tone from the audience's perspective wasn't where you wanted it to be then maybe a 212 would be the better option. Monitoring seems to remain the biggest issue and will probably give you the most bang for the buck in sounding good for now.
Like a laser level, vertically stacking 2 speakers will give you good horizontal coverage at a specific height. 2 horizontal speakers beam like the level rotated 90 degrees, giving good up down coverage but beaming at a specific horizontal point. If you want to use the 212 you could elevate it a bit or use something like an open guitar case to make a little ramp to direct the sound up of the bottom speaker. (like a deeflexx)
