The dwell time has got to be pretty short on a 14.5" mid length; it should be a soft shooter. BillyJack have you had any under gassing issues?
I've been seriously thinking about picking up another Spikes upper. I'll be interested in your review of the mid length after you get some range time.
Regarding the red dot, I currently own an AimPoint Comp3, EOtech XPS, and a Trijicon SRS. I think you're smart to wait on the optic until you can afford one of the better ones. I've owned the Vortex Strike Fire, a Burris, and a Bushnell; none of them are as good as the first three. In my opinion its worth the wait.
Currently, the Trijicon is my favorite.
Hk USP 45 Expert, USP 40, USP 9, SIG P226, S&W M&P9, Hk 4, Makarov, Desert Eagle 40, Beretta FS92 Centurion, Kimber TLEII 1911A1, Glock 22, SIG P225, 1943 Rem Rand 1911A1, S&W mod 64, Walther PPQ, SIG P229, Browning BDA 45 (SIG P220), Hk45, SIG P230