This is a small annoyance; I use 232,228,216 as the background colour in my windows, and x2 changes this on the background of thumbnails to a rather different peach colour.
You can't see it in that screenshot, but the toolbar icons, when text labels are enabled, have a font that looks too be about five or six point, which is not quite readable (this may be due to my using a seven point menu font).
Also, I tried the modified icon I posted before, it takes about twenty kilobytes off the executable size.