Totally agree with Phil here, been in a couple of similar situations, i play Deep House/bit of Techno, which a lot of my mates love but when you’re playin a 30th birthday or watever, not everyones gonna like it! So in the past friends have asked me to play some indie etc. at the start of the nite and go nuts later with watever i want, i accepted the challenge and had a ball! Played lots of Roses, Bowie, Primal Scream, all sorts, at the start of the nite, just loaded them into Traktor straight from iTunes (i’m sure you can get something similar sorted depending on your software?) didnt really worry about beatmatching and tempos, (trust me, your audience wont care either) and just enjoyed it 🙂 Even started looping and Fx’ing a bit of ‘Fools Gold’ and it went down a storm, so basically just have fun with it, then later in the nite when everyones well on their way, start playing your own stuff, (which i’m sure will go down well as you said your friend likes your Dupsteppy stuff anyway).
Anyway, best of luck with the gig, hope you give it a go and just have fun with it! (and let us know how it went afterwards)
Cheers
Beedle