Getting your figures to be featured in other people's rules sets is a very good move.
6mm sci fi has the benefit that you have the ability to use some very large models which simply aren'y feasible in larger scales. However, Fantasy monsters can all be well represented in 10/12/15mm without breaking the bank (or the gaming table). As such its far harder to "sell" the concept of 6mm as having its benefits, whilst keeping its clear definition from historical mass combat.
In my experience, 6mm fantasy suffers worse than any other area because of the classic bias towards 6mm. Fantasy gamers like to have character in their armies and be able to see that they are "different", "otherwise they may as well play ancients" - phrases I have heard many times over.
Combined with the lack of anything truly huge to be eye catching, you need to do two things - show that your models have great character & detail beyond what most fantasy gamers think 6mm is capable of (which yours do) and show them in huge armies to make people see they can have that character on a massive scale, which just wouldn't be possible in larger figures.
So basically, after that little rant, I return to my original statement - getting your armies and figures represented in other people's games is a great step, but make sure you provide them with enough models to look impressive in an army shot, and enough detail on a few paintjobs to make people reading it go "wow, I didn't realise that was 6mm...."
Good luck!
