I've never had a 5B but I've had two foray's into 1/5th scale, FG Marder Race (pants, end up spending a fortune replacing most of the damn plastic bits with alloy stuff) & MCD MT. Early 5B's had their issues apparently but the latest one's seem pretty robust and if I was going back to 1/5th it's probably the one I'd go for.
Basically went back to nitro as there wasn't a local club for racing 1/5th, different kind of fun to a buzzy nitro but you've got to love the run times and ease of maintenance, oh and the huge rooster tails you can get with a large scale 2WD.
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Losi Eight T - Nova Rossi P21-7T- Hitec 5955's & Spektrum + TeknoRC Losi 8ET - Neu 1515-1Y - MGM 16025 & Hitec 5995's.
RC Heli's - Align T Rex 600 Nitro Sport - X-Cell Spectra G gasser.