I have the Tascam DR22WL, and I am still on the fence about its value. I will confess that I almost always forget I have it, and use a different configuration, but I still hold out hope that it has a place of value, and as you mention I think that place is using it as a remote deck with the internal mics. I do think those internal mics do as good a job as any I have heard (and I have a lot of decks...
), and the advantage is all about placement, sliding that deck into a sweet spot somewhere and controlling it form my phone. The few times I have done that, the result has been pretty good too, and worth the effort. (Location, location, location)
But I still am really unsure about the value, especially if dollars are tight. Used like the DR-05, I am sure it is every bit as good. Used are a remote deck, yes you have the potentially big advantage of finding the sweet spot or a sweet spot (because there will always be great differences of opinion as to what the or a sweet spot is), and I guess my biggest concern is that the deck's Wi-Fi to me is still quite unreliable.
I have the latest firmware and I have the latest app, and I have an android Samsung GalaxyS7 phone running nougat software. That just changed so maybe it helps, but in running the software with marshmallow, the app always froze, every time I used it. The good news is I always had ample time to start recording and tweak levels, but at some point the controls become locked and my Wi-Fi connection while still complete, unusable. The deck always continues to record, so no real harm, but if It is a multi set or multi group show, I'd be unable to make any changes without getting the deck and rebooting. This is very disappointing and perhaps the apple app is better, but at this point for me the Wi-Fi is just a gimmick, and one with potential, but not one I would feel comfortable relying on. If you have a Wi-Fi deack, it'd be nice if the Wi-Fi were rock solid in linking to and staying linked to the app.
So this may or may not help you decide, but this is my impression and experience. Hopefully other purchasers of the deck will chime in. I should mention I paid $110.00 for mine quite a while ago and often see it for even less than that, so you may want to hunt around. I seem to recall you could find it for $140. when it was first released, and it has steadily dropped in price.