I think you are following a dangerous path my friend :d.
Most people are unable to go back after having tried the better headphones, even when they are not THAT much better sometimes. Most times the upgrade is going to be quite noticeable even when you wont be able to tell the difference is as big as the difference in price tag.
I havent tried any of the new SE shure models but what most people say her eon the forums is that they scalate quitye well, with the jump from se420 to se530 being very important. That is the same with Ultimate ears too. Going freom the SF5 to TFP is, apparently, huge.
That is not the case with sennheiser and say the models HD600 and HD650, where the differences according to MOST (and there are no definitives in this, so I think going with what the majority is saying is the right thing to do, given that you dont have access to try equipment) are there but not necessarily favoring any of the two as being better.
If you are having those kind f questions my recommendation is that you avoid the ling path and get the se530 because eventually there is where you will end up. Or you can be lucky and try the se210 and be extremely happy. That is unlikely though.
Good luck...and eventually enjoy the se530