I've considered getting an alt, now and again. I love Allegory, I really do, but she's a little limiting. You see, there are certain things about her that are strictly defined.
First off, her totem animal is (and has to be, it's wrapped up in her name) the alligator (or crocodile, in this case there is no distinction). Me, I'm much less scaly, more furry, and mostly not much of a predator (not a straight up prey animal like a bunny though, which is a bit better- I don't really need to be more timid). This means a) her colour is most definitely green (alright, brown was an option, but, uh, no. I detest brown), and b) she is way more fierce than I am. While I don't wear skirts often, she wears them less (mostly only to Caledon or Babbage, and even there she often crossdresses). So many pretty frocks I'd flounce about it, just sit in her inventory because they just don't fit. She also looks just plain wrong when I try to put her not in a mohawk- great for everyday, less great for fancy dress parties when you aren't actively crashing (versus invited, not as in "SL crashed again"), or historical sims (that, again, you aren't actively trying to subvert in a way. I don't actually mind wearing the left of normal to Caledon and Babbage that I do though). Add in my own dress sense, which is primarily monochromatic to the dark end of the spectrum, and you've excluded a vast amount of the things out there.
While I don't role play, I do tend to be a little...different when I'm Allegory. Not in a huge way, but I do talk a bit more (I'm not very social, and pretty quiet most of the time), and I tend to let her say more of the things that I tend to not say because I'm not sure how they will be taken (read: she's a smart ass, there are lots of random things that get said, and the occasional lascivious comment happens now and again. Still not as much as I think, because I have a filthy, filthy mind. Nevermind that trying to cybersex me is the fastest way to /ignore).
She does tempt me to upload very odd skins for her (not counting the dramatic makeup, that's perfectly acceptable, and something I'd probably continue with an alt), and make me dearly wish I could manipulate the face mesh (I might, perhaps, hinge her mouth like a snake now and again. But really, generally the limitations put on the avatars irk me- from hand and facial meshes being so limited, as those are THE two places people express themselves, to limitations on animations themselves, hand control being unspecific [and broken], inability to mod anims once they've been uploaded at all [hand position, priority, looping, would all make for a lot more flexibility and ease of use]).
Bleh. And after a day of fighting with my dying mouse (at least some small amount of progress was made...on things I may never finish), I'm out.