I think this has evolved into two points, the first being travel and the second being tactical advantage.
I would propose two types of module. The first being a travel mod, it reduces combat effectiveness and defence but increases speed. This is the Indy speed mod.
The second is the combat speed/jump mod. This reduces parameters such as cargo space, increases your hit size and maybe affects armour/shield in some way. This creates a traveller/interceptor dynamic. Interceptors are hit and run, they are there to catch things and maybe take out the Indy travellers or small stuff, they are however paper thin, rely on the surprise, speed and the ability to 'jump' in and out of cover or to move onto terrain impassable by a following enemy.
So we don't have mechs fit with the first mod as it makes you pointless in combat. We do however provide a pseudo class for all current bots (except ewar, they are fast enough and have a defined pseudo role). You won't see this in larger gangs as you are made paper thin, you aren't there to hold the line.
On a side note, this also opens up something I have been toying with in the current mechanics which is based on a fast, hard hitter role to disrupt gangs but in effect is a suicide class. For anyone into Warhammer 40k think of assault marines. They jump over a hill and it's all or nothing, you either picked the right fight or you get a whooping.
All good stuff and if balanced correctly, you could end up with a whole suite of new tactics, strategy and possibilities without having to introduce spews of new mechs, it could be done with two mods