Their section on proper sizing says the XL fits those with inseam 32.5 - 35". Do you fit in that range? Its sizing chart under the Geometry header says it's for riders up to 6'3, but if your inseam fits in the range, you can probably scoot the seat back in the rails and get a bit longer stem and still have a good fit. However, I just remembered that Priority is based in NYC. Why not give them a call or email and see if you can drop by and try one on for size?
If you fit in that range, splash out a bit and get the Eight. Its disc brakes will be so much better than you're used to in the rain. Hydraulic brakes always just feel great.
The L Train looks like a bit more upright posture, which do you prefer?
All that said, I don't think that would be my choice for a city commuter; where's the rack & fenders for the wet days? I'm sure you can add them, but factory fenders tend to fit better.
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Did you look at the Specialized Source Eleven?
https://www.specialized.com/us/en/so...or=80591-36253
It has the Gates belt drive, but superior Alfine 11 hub out back (runs in oil instead of grease, easier to service) and a generator hub up front with built-in lights and includes rack, fenders and belt guard.
It sounds like this bike is something you're going to use until it dies, so it's worth spending a bit to get something really nice and convenient.
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Another great option for NYC might be the Priority Folder:
https://www.prioritybicycles.com/products/folder
It says it fits riders up to 6'4, with its telescoping seatpost and it could easily accommodate a multi-modal commute and will store more easily in your place. It's heavier, but fits in a bag, so is easier to carry anyway.
There will be a bit of a performance penalty, compared to the larger-wheeled bikes, on top of the penalty for internal gearhub vs. derailleur gears, but I bet it's worth it for it being cleaner and so portable. You would maybe even bring it in and not have to lock it up.
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Or how about a used Brompton? Even more portable. (16" wheels) Folds with chain on the inside and rolls on special wheels on the rack when folded. This is maybe the perfect NYC choice; you'd give up some performance for portability.