I am thinking about trying to create a hybrid between the two products.
Essentially I would install them both on the one host account. Their respective databases would be retained as would their administration back ends. However, I would place OpenCart PHP calls and loops within ModX Snippets and place those within my ModX Template. I would even create my open SQL queries in snippets if need be.
Has anyone done this before? Are their any difficulties I could come up against?
Did something like that with prestashop.
Both, prestashop and MODX are livin side by side and share the same database and some Cookies to get the current cart and user-id.
prestashop is installed in a sub-directory (/shop) inside the MODX-directory.
MODX is initialised within a customized front-controller and this way availiable in all presta - controllers and modules and smarty-templates.
This way we can run snippets/ get chunks at all places inside presta where we need them.
We create the header,footer and parts of the sidebar for both, Prestashop and MODX via MODX-snippets and chunks.
All stuff, which is related to products, shoppingcart, checkout, usermanagement and all that is done by presta the usual way.
We have created a xpdo-schema of all presta-tables, so we can use for example migxLoopCollection to get everything what we need from presta inside MODX (for example hooking parts of the product-category-tree into our pdoMenu-navigation)
Its also possible to manage parts of presta-tables (some special products) in a MIGXdb - CMP.
Prestashop and MODX are playing nice together this way.
Not sure, how this would work with OpenCart, but can't say a reason why it should not.
