Operating two separate decks has NEVER been an issue for me, especially if you know the recorder well! So just keep playing around with your new deck[whatever you end up getting as a 2nd deck] and it'll just be second nature to check levels on both decks
And record in 24Bit like Tonedeaf said, and you wont have to monitor levels nearly as much, since getting close to 0db doesn't matter in 24bit, like it used to in 16bit
So you can set levels conservatively and worry a LOT LESS
And IMO, the 44Wl is a waste of money, since you can only use 2 of the channels with external mics/preamps/etc!
I agree with LifeInRewind about the 70d! You can run both sets of your mics straight into the 70d preamps if you wanted/needed to, and can run your M10 as a backup to whatever mics/preamp you want to, with the correct Radio Shack splitter! I split the signal of my VMS02IB preamp with just some Radio Shack RCA splitters, and can EASILY run an M10/R5/DR2D/etc as a backup to my 70d very easily from splitting the output of my VMS02IB! You could do the same with one of your setups and always have the M10 backup in case anything happens to your 70d source
I ran my old M10's as a backup to my 70d for over a year, and I never needed to use the backup M10 source EVER {**knocks on wood**]
I mean yeah the 22/44WL are cool and all, but you can only use 2 channels of your own external gear/mics/preamps/etc, and HAVE to use their internal mics if wanting to do 4 channel! And is it really that hard to personally walk up and check levels at the show? LOL! You should be near your gear anyway unless you are going to bathroom or getting a drink, or are at a festie! It would be AMAZING to check levels while you were taking a piss or getting a drink, but it sounds to me like the WiFi range is that capable just yet, so if you have to be within 25 ft or so to use the WiFi, then its kinda pointless IMO! Certainly not a deck tailored to our needs! But if you only want to do 2 channel, then the 22WL would be pretty cool to play around with! However, we already know the preamps in the 70d sound pretty kickass and it can do REAL 4 channel recording, without having to use internal mics on 2 of the channels
So its really up to you and your needs and wants