Sounds like a great application for colored coins (on whatever crypto platform)!
With Bitshares you would have additional income from the referral program: The more (active) users you get to download the Bitshares client the more do you get paid. A lot of restructuring that is geared towards businesses that use Bitshares and bring in users is to be announced this summer. I would strongly recommend listening to the hangout with Bytemaster where he explains the referral program:
https://beyondbitcoin.org/developer-hangout-with-bytemaster-april-24-2015/Instead of applying for a delegate positions like it has been in the past you get paid per user you sign up...
Another point might be the growing infrastructure to verify users (if you need to know whether a user that participates in a poll is a unique user etc.). Adam Ernest (look for Hangout with Adam Ernest on beyondbitcoinshow.com) and Moonstone / Bitsaphire (
https://youtu.be/-sDU-ooXq-E?t=20m23s) working on id verification.
Moonstone might be interesting to integrate with too (see the video about moonstone above; somewhere in there he also talks about the modular design (freebieservers could be installed as an extension if you have more than UIA) and moonstone will be able to hold bitshares, any bitasset as well as Bitcoin so you can bring bitcoin holders to your platform). The moonstone interview was worth listening to in general...
Just a few thoughts