The DT990 Pro is open. Though that bass isn't open like.
I don't know how you can possible think the Q701 is mid recessed. It's slightly forward from balanced. You just may not be used to it's huge soundstage which doesn't place sounds directly in front of you. That is one complaint people have with the AKGs.The soundstage to some people sounds unnatural, making pretty much everything sound further than it is. I don't agree with this, but we all hear different.
The M50s are mid recessed by nature. As for the M50s, to me the mids recession is slight in the overall scheme of things. Certainly a lot less recessed than some bass/treble heavy headphones that cost twice as much.
If bass and treble is boosted on ANY headphone, mids are automatically going to be recessed. There is no objection. Some headphones pull it off better than others, but it doesn't change the fact that two boosted frequencies will always make another area recessed.
Boosted bass and mids = recessed/smooth/veiled treble
Boosted mids and highs = bass light
Boosted lows and highs = mid recessed
That is an absolute law in headphones.
If one frequency is boosted and the others are on the same level, it's usually considered quality. The Monster Turbines have boosted bass, but balanced mids and highs (documented, and I fully agree having spent the day with them). It's a pretty good sound signature. The HD598 is boosted in the mids, but balanced in the bass and treble. The HD598 is the best alternative I've heard from the Q701, if you want more mids.