Sorry for the delay in response, I didn't see the question till now...

I've got the RX8 in my buggy and the Castle in my truggy. While they are similar vehicles, I've always preferred the truggy as a vehicle to the buggy. I have a tendency to also believe the philosophy "If it ain't broke, don't fix it" so I've never run anything but my MMM/Neu combo in my Losi 8T 2.0. The buggy came with the Losi system and I upgraded to the Tekin. I do feel the Tekin is very precise but I also feel that the MMM/Neu has more kick to it. I think my setups work well for me, the buggy requires more of a delicate hand and the RX8 suits it well. The truggy can be pushed a little harder and I like the MMM/Neu in that. I think the good news is that both systems are excellent and you can't go wrong with either.