I'm of the opinion that it does matter. The panel quality and capacities are critical, true, but the logic board and sundry electrical components which drive the panel are just as significant.
The specs for this Acer XG270HU are advertised as 27" 16:9 WQHD(2560x1440), 60/120/144Hz, <1ms, G-Sync ... all the same as the Asus PG278Q, except it promises the wider viewing angles and colour depth inherent to an IPS panel, and with an even higher insane price tag.
Asus has demonstrated their ability to design, improve, and build cutting-edge tech for years. Albeit primarily on overengineered motherboards and graphic cards, not so much on monitors and peripherals. Their ROG-branded products are ridiculously robust, they overclock (or factory overclock) well, and they consistently offer only the very best quality in every part. Expensive, too, and even though you do get what you pay for you also pay a considerably inflated premium to sport ROG gear.
Acer has demonstrated a mastery of low- and mid-end computer manufacturing for years, able to deliver economy and value to market segments where price point is all important. They have never fared well with their enthusiast or high-end niche offerings and they have a well-established (if perhaps unfair) reputation for making cheap junk. Acer products are notorious for being built around bottom-binned components which can only perform reliably at their minimum rated spec. No "future-proofing" buffer, no overclocking potential, only cheap and basic performance and some tendency to break easily. Acer is an economic innovator, not a technological one, and their attempts to add new cutting-edge functionality tend to fall somewhere between mediocre, uninspired, and useless.
These monitors target enthusiasts interested only in high-performance, high-reliability, high-quality gear, a customer base which is very particular about needs/wants and willing to pay exhorbitant prices to attain top gear. Asus is a pioneer and leader in terms of communicating intimately with this market segment, of shaping their top-tier products with exactly the improvements these customers want, and of enthusiastically embracing modding and overclocking and record-breaking performance, their support has real substance and they are highly motivated to make their brand something (expensive) to brag about. While Acer is just a big corporate OEM/ODM trying to feel their way into an untapped and potentially lucrative market.
I might be wrong, this XG270HU could be a phenomenal monitor (and it better be, for that price!). But I expect it to be as cheap and junky as everything else Acer makes, I expect it to cut corners (and my experience is that once a company is willing to cut a corner, they focus on sparing no expense in cutting every corner possible), in short, I expect it to be plagued with issues and ultimately fail. While I also expect a PG278Q would perform admirably under hard conditions for many years.
I challenge Acer to convince me otherwise.