If it were me, I wouldn’t risk it. The MODx Tiny set-up is very particular to MODx, with long file paths and all kinds of issues relating to PHP settings and such. So I think bringing in the new one could break it. I hope I’m wrong, someone else may chime in. In the past, I’ve done some Tiny/MODx config hacking, and while I got it to work, I did not enjoy it at all.
I got much better results when using Wysiwygpro and doing fancy configs with it. They have a MODx plugin, but it is a paid program, and although I think it’s hot, try getting people to pay for it.

My work with that was pre-Evo, so I’d ask the developers if they’ve used it with Evo - I bet it would work fine.
I kind of feel your pain there, using any kind of WYSIWYG editor in a content management scenario is fraught with pitfalls. I’ve even written articles about it. Good luck!