"i saw in another forum that european airlines changed the carry on size limit, so i can't get the original RS carry on, right?"
I just checked the website of 6 major European airlines (LHA, BA, AF, SAS, KLM, Swiss). If anything, they have added to the dimensions a little. A couple have gone from 15.75"W to 13.8", but they've increased the depth to 9.1" from less than 8", which increases the x-sect area. All the airlines seemed to have increased the x-sect area and the volume a little. However, all but BA hold to the 21-5/8" long restriction.
The Classic Back Door bag (is that what you mean by original, meets the requirements of all six airlines).
Again, as long as it is a soft sided (ie, non-wheeled bag) and not stuffed, it should conform to almost any sizer.