Yes, I generally limit myself to no more than one track day a month although it's two this month
BMW Minis would be offered a friendly welcome, I've turned up a few times in mine to help out and people have been disappointed that it wasn't going on track. It's still a car that's manufactured in the UK so most people are happy. You'd have no more banter that I already get from MGB drivers etc for driving an MGF that they believe is not a real MG.
We often share the days with Lotus-on-Track and there's no better feeling than passing an Elise although they're not best pleased but it still only results in friendly banter. Our main objective is to have days with similar powered cars and courteous drivers.
Come on folks you know you want to.