Yes, as others have said this subject has been discussed at length. And usually I contribute my 2 cents. Once again, I will say I will never buy another MB or MBP unless it is a 17" antiglare. When my 2009 model bites the dust, I will spend the $7200 USD and purchase the Venom Blackbook X, which is a Windows based machine, but at least it has the specs I can only dream of in a MBP. I would gladly pay Apple $10,000 USD for a MBP equivalent to the Blackbook X.
In those seven years so much has changed with the rMBP line up. I, too, was a 17" 'only' until 2012. I kept my 2011 17", JIC ...but - 4 month later I realized I'd not used, turned on or updated my 17". I understand the glare concern, though Apple's done a LOT to negate the effect of mirroring yet keep the positives that everyone enjoys from a vibrant, accurate and dynamic display with HiDPI, pin sharp resolution.
Others have mentioned it, displays externally are well priced today, even the 4K displays. If your display is of concern a couple hundred bucks will get you Anti- Glare 1080p, while under a thousand dollar price tag provides dozens of options including 4K/AG.
As an aside I've owned the 2012 15"/16/768 since release and it's as quick and trouble free since day one 3 ½ years ago. I picked the 2015 15"/16/1TB @ Best Buy on a Christmas sale for nearly $600 off. It was on sale $400 off. If you spent over a thousand you got a hundred off your choice of purchase and a hundred dollar gift card. Apple wanted/wants $3199 for the same rig ...and I'm satisfied with the incredible speed of its storage, AMD's card saves me a LOT of time using After Effects, transcoding ...other facets of video and audio editing are wickedly quick. I've also a 27" display as a 'dock' at the home and studio that also allows for thunderbolt to Ethernet wired.
My cent and a ½. I'd never spend 10k on any computer, so perhaps we won't see eye to eye but the 27" iMac @ 5K is a helluva machine. You can spend $10k on a Mac Pro and while I'm ignorant to the machine you're considering, the opposite is true when it comes to the 15" rMBPs.
The transition itself in 2012 was enough to reinvigorate my interest in 'hobby' computing again rather than just using a 'work' console while at work.
Ymmv, but IMHO, which should certainly be taken as pure guessing ...we won't see any 17" models again. Never know. Enough screamed and through tantrums about 4.7" -- now Apple is supposedly going to cater to them
Problem with our desire, we aren't the majority and larger than 13" computers are becoming rarer and rarer by the day.
Have you played w/15" rMBP? You're able to scale it up to 1920x1200 ...the resolution I've always used on mine. And coincidentally, it matches the rez of the 17". Less real estate for those pixels is negated by its intense clarity and high resolution as well as its scaling algorithms - an issue still in play on Win 10 with legacy software (I'm ambidextrous and again, IMHO, the rMBP is the best Windows machine on the market as well

-- we've got a couple of Win boxes and it's up to you your pocket book and needs ...as far as I'm concerned, Windows is a weird place right now sharing the OS with phones, tabs and consoles as well as X86 hardware seems a bit over the top. Time will tell and 10 is much better than 8.1.
Good luck though, as four top spec'd rMBPs may make more sense than a ten thousand dollar one that'll run Windows and depreciate quickly in price and relevance as all tech does