As my style of backpacking doesn't even remotely justify a $600-900 tent, I have about 10 ranging from "inexpensive" to mid-tier "cottage industry" along with several Naturehike like the Mongar 1 UL. That, and the Pro 1, are both extremely well-made products and IMO, a far better value than the far more expensive and less functional MSR Hubba Hubba look alike. (I'd also take the NH over my friend's weird yellow BA.) Truth is, on the cost/quality curve, NHs' constantly improving products and workmanship is hard to beat and now compares favorably with the best. And while I like the UL, at 6' it felt a bit small and the 1,500mm, 15d fly too delicate for my needs. The Pro solves all this with 20d 3000mm fabric, more robust zippers and a ton of extra room at little extra weight to where it genuinely feels like a 1.5 tent. The poles and connectors also appear sturdier and because the tent is wider & longer, they are also under less bending stress. The beige colored inner nest is restful and reflects a night light well and the two "ported" end storage nets are ridiculously huge.
Another often overlooked thoughtful design feature is the vertical door entry that really helps prevent rain coming in with you. It should also be noted the Pro's fly and porch mode provide greater coverage than the UL and will likely be more comfortable in windy or colder temps. I've not yet done a rain test but past experience with NH suggests all will be well. So, other than my preference for slightly larger fly buckles for my big hands and a 2nd vent (or kickstand at the top of the fly zipper), I really don't see any deal breakers or much room for improvement on the Pro.
IMO, the Pro 1 is perfect for the weekend hiker who wants to enjoy being outdoors and not have it be an endurance test. (For the gram counting thru hiker, the UL is likely the better choice.) However, as the weekender also needs to carry less supplies for shorter trips, the Pro's few extra ounces balance out and are well worth the increased comfort, usefulness, durability and water resistance. Good job, NH!