though who doesn't love wobbly windows?
I don't, but that's beside the point.
I only use Cinnamon, not Mate, but I haven't read about problems mixing the two myself. Are there any specific posts you have read on the forum about this? I was also under the impression that Cinnamon used some other graphic accelerator (clutter, mutter, flutter, something like that - shows how much attention I pay to graphics effects). Or maybe that is MInt 14 not 13. Personally I would just give it a go it is easy enough to remove the one you like least. Better still if it worries you have a look at QT4-fsarchiver or clonezilla, make a disk image and if anything goes wrong with your dual desktops just put the old image back again. It really is the only way to work with Linux (or any other distro for that matter).
Fujitsu Lifebook AH532. Intel i5 processor, 6Gb ram, Intel HD3000 graphics, Intel Audio/wifi. Realtek RTL8111/8168B Ethernet.Lubuntu 13.10,Ubuntu12.10 (Unity), Mint16 (Cinnamon), Manjaro (Xfce).