The ONLY thing stopping me from using Kickstart is sales taxes. Taxcloud is available for Ubercart as of a few weeks ago. This is sad as the future is clearly with drupalcommerce. The module installs but gives some error about dependency names. I hope the ones responsible for developing taxcloud for Ubercart will make sure it is working in Kiskstart. In Oklahoma, we have 816 sales tax zones and more being added monthly. I need this soon. Tax Cloud is keeping me with zencart. :-(
Avalara is a great option too. Though they are not free, they do have some surprisingly competitive offers, great customer service, and is very scalable.. Alvalara is also the market leader in terms of Shopping cart compatibility.