I have an older sand 13" Mk4 and love the design, the feel, and the look of the rail. I'm building a new 5.45x39 rifle and I wanted a Geissele Mk4 9.5" and have no use for key mod. I just received a new Mk4 and I was disappointed to see it was the Keymod version. I have to say I almost sent it back. Compaired to the sleek lines and low weight of the pre-Keymod version this thing just feels clunky. I'm not asking you to stop building the Keymod version, I am asking for you to bring back the original Mk4.
My favorite rails by far are the KAC URX 3/3.1 and the Geissele Mk4. I've tried a Noveske NSR 15". Had it on for a week and promptly removed it and replaced it with a URX 3. Just don't like the feel or look of Keymod. I know I can put covers on it, but with the older Mk4 I don't bother with covers.
I'm a huge Geissele fan (14 triggers and two rails plus some ALG stuff) and will continue to be. Please, bring back the old Mk4!