Currently, the only things I think are clearly missing from S-Gear are stompboxes to load before the amp, and a good 5150-type amp.

Stompboxes:
I don't care if S-Gear offers a huge range of stompboxes--I'd rather have a few amazing options than a mangerie of marginal, gimmicky ones. But a good tubescreamer style overdrive, a good RAT or Boss DS-1 style distortion, a fuzz, an MXR style compressor, and a wah-wah, would help a ton. Obviously, the wah-wah would be best if it could be automated or controlled through an expression pedal or a MIDI control surface.

A 5150 Mod for the Jackal
The Wayfarer does a pretty good Mesa Boogie Mark high gain tone, but the Jackal's Soldano tone sounds, to my ears, still pretty modest (like it's on Crunch rather than Lead). As I understand it though, the Peavey 5150 was based heavily upon the Soldano SLO. The chief difference between two being that the 5150 had an extra gain stage and some extra solid state stuff to shape the tone a bit. So, if it's possible to tweak the Jackal to add another gain stage and give it some of that 5150 character, that would be ideal!

Right now I use a WAY HUGE Overrated Special in front of S Gear when I need it. And even when I do not need it

I like the 500hz and the tone control. It makes this pedal very versatile.

In S Gear I would see an overdrive thing with some sort of graphic equalizer incorporated (Like the Archer Steve Stevens) , Volume, Tone and drive , and the the possibility to save two settings like the amps in S Gear. The basic Overdrive thing would be like that and you would chose what type of overdrive you need for each setting. This way Mike could start with a simple and more common overdrive type and could add some others (Like a Dumble type etc...) down the road. Or even incorporate a basic one in S Gear and sell the optional ones for people that need more.

A small but useful set of stompboxes would be great. Many of us using S-Gear for recording can do reverb, delay, flanging, chorusing stuff using other DAW plugins, but "before the amp" stomp boxes for overdrive and fuzz/distortion would be very useful for tone shaping.