All I know is what I read about them in the VMX mag feature on the 79/80 model YZ250s a few issues ago. Apparently the 78 has a real "roadrace" type top end-ish power delivery if I remember what I read correctly. The '79 and '80 models were obviously improved bikes, but you'd expect that.
You'd have to ride it in the evo class, which some people see as a problem given that you'd be riding against later model bikes, but I don't think it matters a bit. I managed to keep up with a young fella on an 87 CR125 on my 79 YZ125 at the QVMX meet at Biddabadda/battered sav or whatever it is. Having said that, there's plenty of riders pass me on much older, supposedly less competitive bikes every time there's an all-in race, so it just comes down to the rider.
If you can find a bike, and you like that model, go ahead and buy it. There's too many 250 G's and H's out there anyway
