Anyone ride the Kokopedalli no-drop ride w/PMBC? (Phx area)

I've just been getting back into cycling over the last couple of weeks, and have been thinking about doing this ride. It states it's 20-30 miles at 10-14 mph. My last couple of rides, I've done 10 miles at about 10 mph. The last couple of mornings I've felt like I could do more (feel tired at the beginning of the ride, but by the end I'm kinda in a groove and ready to keep going), but time limits me, so I haven't really been able to see how far I can go.

Saturday will be my first opportunity to ride as long as I can/want to, so I'll probably just go on my own and see what I can do, then maybe trying it the following week (if we aren't out of town camping, that is :) ). I know being with a group will naturally push me further/faster than I can on my own. I know it's a no-drop, but I'm afraid of being that person that people are secretly (or not so secretly) wishing hadn't come.

Also, I'm riding a mountain bike with knobby tires (very worn on the back, they *really* need to be replaced). I want to put some road tires on it...will this give me a noticeable increase in speed?