I recently bought one of these Aero Sleeved Tri Tops as it was on offer.
Reading the previous review's, it seems there is an issue with sizing. However, I have been using 2XU apparel now for over 4 years and I am a size medium across their line of apparel whether it be tops, tights, jackets or shorts so stumped for the size medium for this Tri top hoping it would be true to size. Sure enough it is true to size but I have to say that yes, it is a bit of a task to zip up but once done up it fits a treat even with a HRM strap underneath! The zipper is a more heavy duty type than you would expect from other Tri tops I have used such as DhB but the fit is more skin tight or "aero" as it states in the title.
I do ALOT of trail running in all conditions and wore this top recently along with a pair of 2XU MCS (Lightspeed) tights in temperatures of around 9-11c and very little wind through pine forests and beach with no issues. It is breathable, lightweight but seems extremely well made. The cut is aero and does not extend too far below the waist. It regulates body heat very well indeed and I did not need any other layer for the 2 hour trail run. I also used the small rear pockets for my energy gels too.
Overall, it is an impressive garment for the activity I undertake even though it is not designed for trail running (I wish 2XU made more trail running specific garments in their compression line-up and would like to give them some input/feedback on this subject) and I would say goโฆ