I *prefer* the idea of getting topped by a TS. The idea of being pegged by a bird is OK but not quite 'different' enough to excite me. I let a WG do this once, she had no idea and really hurt me. So I think I'd rather someone who knows what they're doing 'do it'
I say 'prefer' because I've tried twice now, only to bottle it and leave (after handing over the £££, stupidly-I guess I did waste their time though tbf). Not sure if it was because I thought 'shit they look too much like guys in wigs/ makeup', or because I thought 'let's call a spade a spade, shit I'm about to get fucked by a dude). I submissively experimented in a very basic fashion with a guy many years ago when I was very high, then freaked the fuck out when I sobered up. So I can't say it's an area I'm even marginally comfortable about exploring further.
But I can still get off to certain feminine TS porn when I'm in the mood, and still feel compelled to find a properly feminine but functional TS, just to 'know'.