I'm trying to make a decision between Drupal 6 + Ubercart and Drupal7 + Drupal Commerce... I'd much rather develop in 7 and am excited about Drupal Commerce but, as it is relatively young, have some concerns about its security and stability.
Does anyone have any relevant experience they would be willing to share?
The payment gateway is the key. If your chosen payment gateway is available for Drupal Commerce, I would say yes, go ahead and use it.
Even if not, there are compelling reasons to develop or help to develop the payment gateway.
Drupal 7 is much more advanced, and will continue to be relevant for much longer. Drupal 6 will not be supported when Drupal 8 is released. Suppose Drupal 8 is released in 2 years (nobody knows at this stage but it's a reasonable estimate) and your site takes 6 months to launch. A Drupal 6 site would only have a viable life of 18 months. It's something worth considering!
We're building a reasonably complicated Drupal Commerce site right now and the elements like the order system, cart, checkout and things like entity types are all fairly concrete. It's also slick to use, and offers numerous advantages over Ubercart (products do not HAVE to be nodes, opening up new ways of selling things).
We're running a project with Drupal Commerce and it a great base for a store, but I'd say the key decision whether to use it is how comfortable you are with development. Commerce is a well designed e-commerce framework done the "drupal way", but unless you're comfortable with writing some custom modules to fill the in the gaps it's a lot slower getting up and running then UC. If UC has what you need out of the box it's likely the way to go from a time-cost of development point of view. If you're looking for long term longevity and future upgradeable of the project and you're ready to do some custom work then consider commerce.
For our project the store we're making is very customized (you order prints online) so commerce is an excellent framework to build on. But if you need something more simple like a say a clothing store, the current way you make a product in commerce is cumbersome. To create a basic product you need to create all the commerce "products" (EG product variations or SKUs) one at a time, in a commerce product type, and then you relate them to a "product view node". When a shopper sees a single product they see the product node view, which bundles up all the (commerce product) variations. There's logical reasons to do this but its slow to enter the data.
This is a lot more work - make all the variations, and then link them to the product. There's some contrib modules out there to help this but commerce is a fast moving target so you'll see commerce updates break these modules - so that's where your ability to modify / write modules becomes important in deciding what system to use. Commerce will be likely be more challenging to develop in right now - as it's got it's own learning curve, but its nice that basically everything is there is now drupal core stuff : views, fields, etc. So if you need flexible expandability in the long run commerce is great, but if your store is not likely to require future functionality enhancements and UC does what you need out of the box then I'd suggest going that direction
Commerce Kickstart 2 hit its 2nd release candidate yesterday so I would consider it stable to start working with. It is also very actively maintained so I guess there will be lots more bugfixes rolling out over the coming weeks as you start building your site.
I have used it for an upcoming project and it was a major help in boosting development time. It allows as much modification as you like but does include many dependent modules that are difficult to remove as they are part of the core features of kickstart.
Basically, yes, use it but dont install the demo content as you will be stuck trying to remove it.
I have been using Drupal Commerce for several months now. I have not have found many troubles so far. You should take a look of the videos and the documentation commerce guys has and find out if this module will be a good fit for your situation. I love Drupal Commerce. It really helped us to do our solution with the time constrains. I have never tryed ubercart though. I would have loved to have the time to try Ubercart and make a comparison. For my needs, it looked like Drupal Commerce had everything I needed. So, I never give a try to Ubercart.
Here I leave you with some information that helped me out with Drupal Commerce.
I love the integration that it has with Views and there are also modules that help you to extend their features as commerce cart ajax, commerce cart expiration and Commerce Stock. You can customize commerce but don't do it in the core use the best practice of Drupal. I did several customization for my project. I even had to do my own expiration cart because they did not have at that time a cart expiration. I love the way you can also integrate it with Rules. I love the flexibility that this module has given me.
