Mark,
I took a break from AbanteCart due to the holiday so just got a chance to read your latest post. The code you posted is interesting, but it confirms to me that I'd rather spend my time designing new products for my business than studying & developing code. As much as I enjoy troubleshooting errors -- because that's how I learn -- I really don't want to spend as much time as would be required to get to speed on all the minutiae of coding. I guess I'm not as nerdy as I thought! And the last thing I want to do is have this affect my customer experience while I'm trying to fix a bug or find a solution here on the forums.
So, I've been playing with the Shopify trial, too, during the past ten days or so and I like it. The Facebook & Pinterest features I mentioned allow a customer to purchase my products from within Facebook or Pinterest though the Shopify integrations, so a customer doesn't have to leave those sites at all to purchase from me. It's a convenience for my customers. I know people spend more time on those sites than mine, unfortunately.

I get what you're saying. I'd rather have a customer on my site 100% (where I have complete control of my brand "message") than trying to sell to them on FB or Pinterest. But I want to reach my customers wherever they are and I won't know if the integrations are good or not unless I try.

Two big things I don't like about Shopify are:
1) I can't use my domain's SSL cert. Customers will have to checkout through something like "shopify.com/mydomain" unless I pay for an "enterprise" plan, which is over $1,000/month. Ridiculous and no way a small business like mine can afford it.
2) Email: I have to pay for email service through a third party (like Google Apps) for custom / domain email forwarding.
But I am willing to accept these shortcomings because I know a lot of my customers spend time on FB & Pinterest and I want to see if it's worth reaching them using a service like Shopify.
I might sound like a shill for Shopify, but I know it's not perfect. I really would prefer a solution like AbanteCart. When Pinterest was launching their "buy" button, I actually signed up for their "waiting / wish list" requesting AbanteCart as a partner. But I guess big sites like FB & Pinterest won't support AbanteCart's platform until it gets more popular and is more stable. I don't see that happening for a while.
If I were a dedicated web developer I'd try to work on such an extension for AbanteCart to work directly within FB, Pinterest, or Instagram but unfortunately this is beyond my capabilities. I hope someone on these boards sees this and makes it happen, in which case I'd stick with it.
So I'll keep up with AbanteCart as much as I can. I'd recommend it to people. It's just that I really am itching to try those FB & Pinterest integrations.