Mary Jo Pehl  is now with Rifftrax, doing a series of shorts with Bridget Nelson.

I'm wary for a couple reasons. First, it's the writing team that will matter. Who they get behind the camera. Rifftrax had the advantage when they started that Mike was the head MST3K writer. No matter who they get to host, it'll take a bit for the chemistry to build.

Second... let's face it, this is a Veronica Mars situation. The rights are now owned by Shout Factory, the company releasing the DVDs. They COULD pay for this, but would rather have us foot the production costs. You don't get much in return, apart from the show existing. This actually is a donation. Compare this to the Rifftrax Kickstarters, which shove enough digital goodies at you that you get your money's worth (they use your cash to pay the upfront costs for the live shows).

When Joel created the show, Mike Nelson was still a waiter at TGI Fridays.  Mike is a talented fella, but he wasn't always the head writer - he started as the writing room assistant.   
It's fine to prefer the direction the show took when Mike did become the head writer.  But to say the reboot is at a disadvantage if Mike isn't writing... sheesh, it's Joel's freakin' show.  Everything MST3K is came out of Joel's brain originally.   I'd only be worried if someone ELSE was running the reboot. 
But of course, I'm a Joel guy.  If you're a Mike person your life must be very difficult already, so I will leave you in your freakish misery.