Can anyone predict/discuss the feasibility of using shopping carts created with Shopping Card Creator Pro in sites designed with RSD? Is anyone successfully integrating fully-useable SCCP carts into responsive sites using Responsive Layout Maker Pro?

My gut feeling is that it's a bad marriage that will throw many additional truckloads of dirt on SCCP, given the latter's pre-responsive website origins. I'd like to be wrong, but it seems that trying to use a SCCP cart will destroy the site's responsiveness, at least on the shopping cart pages. That would not be a good thing...

For now it's best to keep these two things separate for the very reasons you have stated.

If you need a simple way for customers to make purchases, you can use Web Form Builder which is fully responsive and has checkout capability built into it.