I don't think choosing your website platform based on which Sixbit will implement first is the way to go about picking your platform.
You should choose one based on whats best your your business.
We went with BigCommerce based on recommendations from people with knowledge in these matters. BigCommerce came in high regards.
Cost was another factor and at $250 a month for the Pro plan, it's a good deal.
Building product pages was a learning curve, but now that I've been thru the ringer, I must say the User interface is very good, and managing products is very easy.
The optional integrated payment and shipping gateways implemented with our existing services (Paypal and Shipworks) super easy.
Now that it's up and running, I hardly even need to log into the site.. (although I do need to add more products)
Realize what John said is that they are working on getting the non-AZ ASIN feature fully implemented, first.
In my opinion, there a lot to be done with that feature yet, so I wouldn't expect to see webstore implementation for quite some time yet.
We're really hoping to see some movement with this in the near future. I have a dormant Magento site waiting for Sixbit to bring this feature.
We're not really looking to change the eCommerce software to anything else as SB is deeply embedded here and we all love it, so Magento integration would be a massive bonus for us so we don't have to go about changing to and learning a new system.
We're not really willing to launch the new 'site as a standalone platform, it would create more admin that it would save.
We're still fighting with Sixbit totally messing up Amazon variations, and that's still ahead of non-ASIN listing creation.
I wouldn't get your hopes up. I mean, how long ago did SB release AZ support? And variations still don't work....
That alone has created a nightmare for us, on Amazon, so I sure hope they plan on getting that rock solid, before working on eCommerce sites....
And then, when it comes to non-ASIN creation....I'm not aware of a single person that's had even one new Amazon listing created from SB.
So, don't hold your breath on Webstore support, IMHO
Personally we are happy with xCart and would love to see integration for it in the coming future. While we also realize that there are several shopping cart solutions I am sure that it is not going to be feasible to interact with all of them. Another of the more popular ones in use is the OSCommerce platform as well as ZenCart.
As in the past John we are available to assist with Beta testing on xCart, OSCommerce, ZenCart or Magento.