The GN2 was my first and (so far only) Android device so I don't know what exactly is Touchwizv vs vanilaa Android. MInd if I ask what about it you hate? I didn't like the default launcher, so I use Nova instead. Which parts do you hate that you can't hide that would make you give up the pen functionality and MultiWIndow?
If you go with a vanilla rom you lose all of the S-Pen benefits which (for me) is the key reason to get a GN3 in the first place. But it really depends on your carrier, if you have either ATT or Verizon you should NOT expect anything anytime soon or ever. The GS4 bootloader has been so far unbreakable and the GN3 is likely even worse.
I understand that it is all down to personal taste but I never found touchwiz to be ugly. My main problem with touchwiz has been how laggy the ui had been, which by all accounts has been fixed but if you do install a stock like rom you will lose all of the features that makes this phone unique. Multitasking is big draw imo.