I love my Ultimaker 2(+)! There is nothing quite like taking the idea in your head and turning in to a real thing you can hold in your hand! ... Plus I get lots of cool and unique toys too. It is lots of learning and trial and error, though, so be prepared to sink some time in to it.
My only complaint with my printer is that my robot project got put on hold as I got distracted with the printer. That was more than a year ago!
To keep this on topic, though, I have never had the urge to convert to 1.75mm and I have not trouble getting 2.85mm in Canada, both cheap stuff and quality name brand stuff. In the US or with having several different printers, maybe it makes more sense to convert, but for me, I do not see much point. Though maybe I do not know what I am missing!
Anyway, hope this helps.
ok thanks i probably will purchase one next year. And same with me i was making a guitar and then i started using my high school's 3-D printer and Solidworks and havent worked on the guitar. lol