I find that hard to believe. Check out this tear down: http://www.mcfrede.dk/projects/takstar_hi_2050_pro_80_design_review/takstar_hi_2050_pro_80_design_review_01.shtml
The 2 are identical except for the grille and dampening.
the headband is different on these two in construction and design... he isn't comparing headbands
just look at these two photos:
the pro80 imo has the nicer looking headband imo, but I am pretty sure it is also slightly shorter. The comarison is simple, owned the 2050 for 8 months before I sold it and got the pro 80 for practical reasons, my ear snips (or whatever, lowest part of ear) never touched the pad of the 2050s but it touches the pad of the pro 80s.
Its not like there is much space for a pacebo effect, it could well have to do with qc and where the stopper for the extension is placed but I highly doubt it since I have had two different pairs of pro 80s on my head and they both were ever so slightly too small while the 2050 had a touch of space to play with.