I too have some interest in gaming Border Reivers. I have some of the Vendels and have been meaning to get some of the Monolith figures as well.
I read the "Hot Trod and Red Hand" rules at Vendel's site but they kind of tapered out towards the end, making them (IMO) not fully playable. It felt like the authors got tired of writing the ruleset once they had the basic mechanics in place and started moving on to the scenarios and campaign system. A crying shame, as it looked promising at first.
I suppose that most of all, I'd like some Border Reivers rules in the form of a supplement for Gloire. Maybe some smallish supplement at 20-30 pages or so, possibly covering not just Border Reivers but all kinds of adventure in the shaggier parts of the Isles ("Where the men are men and the sheep are afraid"

)