Even without the need for IE11, BYOND is nigh unusable on Wine. It runs extremely poorly due to extreme and poor usage of Win32 UI stuff.
There appears to be some form of resource leak in BYOND which causes its Ui system to gradually slow down the longer you're playing. This is severely amplified by presumably Wine being less optimized than Windows in these areas. It means that after just ~15 minutes of playing the client will starts stuttering severely on Wine. Then you need to restart the client which can take 2-3 minutes depending on how broken BYOND's ad loading wants to be. (This also happens on Windows but the effect is MUCH slower so you can go hours without noticing).
We've[0] been at it for 4 years. As Moony already said, development has been faster than ever recently. We've gotten decently consistent player counts now over the past month, and just a few days ago a Twitch streamer Bikeman streamed SS14 to 1,500 viewers (peak)[1].
We may only have 15% of the content of an SS13 codebase but I like to think that we have enough merits like a less laggy engine to make up for that.
I can say confidently that we have definitely broken the curse and short of a suspicious series of bus accidents across the EU, US and AU, nothing can stop us now.