I did own the flares pro and I did like them to some extent, agreed the Bluetooth dongle sounded awful but my Bluetooth journey at that time had always disappointed , until btr5 nothing had ever come close to wired for me although my Bluetooth journey had always been limited.
My main complaint with the pros was a grainy rasping mids/vocals and this metallic sheen to the treble, this sounds worse in words than it was but it was the rasping vocals that I couldn't live with, I even sent them back under warranty to check them, it was actually a very good iem though and if the vocals/mids which should be the star of the show in my eyes had been ok i would of definitely kept them, lovely detail and the sub bass is probably the best I have heard on any iem in my limited experience.
Compared to etymoyic there totally different, firstly bass which the flares are very good at if you like bass , both mids and treble are far superior on the etys much more accurate, smooth and lovely....personally I don't know if you would like etys due to bass and they do lack depth to say something like multi driver andro, dm6 etc etc but etymotic have been doing this a lot longer than most and specialise in hearing products, what makes them excellent for me is there accuracy, its a more 2d sound being a single mico ba but the detail and realism is so accurate to me , when I first got them I described it like putting surgical instruments in my ears, precise accurate and very very clean , micro detail possibly the best I have heard and easily as good as andro or better at this... if I were to recommend to anyone etys , I honestly would say buy from amazon so you can return if not your thing, also give them a chance for you to become accustomed to there sound as it's unlike a lot of iems but if like me you do then you will go back to other stuff and think, these vocals sound wrong or this bass is bloated or this treble is too much, accurate accurate accurate is all I can say ..give em a try is all I can say , I will never sell my er4xr