Ok, I take it back. Funny how things always look better in the morning.
I've tried two models, one with Gryphonne Sepia and one with Devlan Mud (suggested by the GW guy). I really like the effect of the GS wash though I am still upset about the number of coats it took to clean up. At this rate, if I do all my marines in this "basic" way, I won't be done until Valentine's day!
The one thing I like about the GS wash is that it makes it look like I've had a base of Mechrite Red without sacrificing the brightness of the Blood Red. IMHO, a Mechrite Red basecoat will not produce the same "brightness" as a Blood Red basecoat in the end, so a GS wash gives me that Mechrite Red "look" without having to do an actual Mechrite Red basecoat.
Thanks for the advice and support, gohkm and Wicksy. I would like to ignore the washes but at the moment a plain-basecoated mini looks too... incomplete for me.
As I do more and more marines, I am getting a nice "feel" for the final look I want. Still not going for the highlights/shadows thing for now (too time consuming) but I do think I may highlight a bit of my marine armor. So far, my plan is to basecoat Blood Red, 2 controlled washes of Gryphonne Sepia (for less cleanup), touchup with basecoat again (easier said than done!), paint in the details (aquila, soft armor, backpack, skulls), glue on the gun (guns are cleaned, primed, and painted separately), then base.
Now I got 12 space marines on TTQ paintjobs waiting for their base decorations. w00t!