davelarz - did you ask your dealer what he feels the improvements are? You might want to post this question on the forum at the GET website.
I’ve heard the Three, the Three+ and the Two+ - but not the Two. So I can only make an educated guess about the 2+ based on my 3 vs 3+ comparison. And the 3/3+ were close. But the 3+ was better in a couple areas.
The 3 was slightly less open than the 3+, with a hint of extra warmth in the mid- upper bass. (Could be more pronounced in the Two vs Two+ with their bigger sub and bass drivers.) I wouldn’t describe any Triton speaker as "boxy" sounding, quite the opposite. But the 3+ was more transparent and - surprisingly, because coherency was good on all the Tritons I heard - more coherent than its predecessor. I played a CD of Beethoven piano sonatas through each model - the 3+ was clearly smoother with the transitions through the registers, probably due to the new crossovers and dsp processing in the plus series. The way the 3+ handled piano impressed me and led me to audition the 2+.
I"d expect the 2+ to show the same improvements compared to the 2 as its little brother did to the Three: it’ll have everything you like about your Twos but with better clarity, transparency and coherence. Not night and day difference, but audibly more refined.
Have you considered auditioning the Ones? That might be a bigger bang for buck upgrade. As people move up to the T-Refs there could be some good deals around this year. And as you already know, the creation of the One inspired the improvements and voicing on the Two+.
BTW, we thought the Two+ were terrific speakers and plan on buying a pair, although we could be happy with the Three+.