We have a collection of commercial MFC/C++ applications which we sell using Stingray Objective Toolkit, we have source code license and have ported it in the past to Solaris/IRIX/HP-UX/AIX using Bristol Technologies WindU (Windows API on UNIX, including MFC).
Any long story short recently about 18 months ago we ported Stingray to Win64, but a long a tedious task, during this time I did some research on commercial and open source alternative MFC extension libraries things like Ultimate Toolbox and Prof-UIS.
Yes, we haved moved away from Stingray. It depends on what Stingray components you are using. For the grid control, you can use the free MFC gridcontrol from www.codeproject.com or the commercial one from http://www.bcgsoft.com/. The free one is OK but development has stalled, so no modern UI rendering etc.
The 'layout editor' Stingray component can be replaced by the one from bcgsoft.com, but I don't have experience with that - we rewrote the functionality we needed from that on our own (it was only a subset of what Stingray provided).
As for alternative MFC toolboxes, I suggest bcgsoft because part of their toolbox is in the Visual Studio Feature Pack so it's free and fits very well with VS. I have looked at Ultimate Toolbox (stay away from it, stale code that isn't updated anymore) and Prof-UIs (OK but I found it not so easy to integrate).
Now that BCG is part of the 'official' MFC I don't see a reason to choose something else than BCG (except for maybe the cost, if you need a free alternative you can look at codeproject).