well the thing is i'm getting it commissioned, since i can NOT do dresses to save my life >.< especially with as much detail as i want it >.<
but i think ima stick with her default outfit, because that way if i decide to sell it, people will buy it 
and not a lot of people have seen the movie so they may not know who i am if i wear the ending dress >.<
Ahhh, same here >.<! (Hopefully not by the same person? xD)
Yea, I can't sew period (but shhh, I'm Rapunzel, yesh I can....)
I guess that's safer, but she could easily commission the other too. Plus, you can tell the commissioner your envisions on the parts of the dress that are uncertain or your preferences on what you DO NOT want the commissioner to do on "unknown" areas. Most commissioners are fine with that so long as they don't have to do lots of changes once started or half way or have some creative mind in the creation (everyone is different). It shouldn't cost you extra either.
Also, I'm sure people will recognize, but if not, there's also other indications you could have like have a stuffy Pascal on your shoulder or have a Flynn with you, whether in normal outfit or ending sequence outfit.
I'm just saying, obviously you've made your decision though, which has its good points, but I think it would have been cool to see the other dress just cause I don't think I've heard of someone making that dress in particular yet ^^
