I agree Johnny to me its just a trail bike and a over rated one at that .Did it ever win anything ?
A few good MXGP finishes and US 4 stroke nationals, it could be argued that it was hugely successful in MXGP given it was up against open class 2 strokes. Along with the 70s Cheney's and CCMs, the HL was a last gasp attempt at building a competitive 4 stroke in a race environment dominated by 2 strokes.
The ProTec bikes were special in so far as they were highly developed and had top US riders on them to compete in the 4 stroke nationals so have a place in MX history. The 4 stroke only US events as with the 4 stroke nationals in Aussie were very high profile and had some really top US and Aussie riders for that matter competing on HLs, C&Js and the like.
I agree with Son and Tahitian Red in so far as the C&J was probably a better bike, could have something to do with how the XR motor carries its weight lower, is more compact and like you say 2 years was a long time in the 70s.
The ATK connection with this bike also makes it much cooler. The sister ProTec bike to this one that I beleive Rick Johnson rode, was once on the market at 50K. Saying that it is worth replacement value plus change must be just a comment to wind things up, its like saying there is no value in a bike with race history which is completely not the case.
I see HL reps being one of those things you own, a bit like Cobra reps, because you can and they have a certain iconic status. Also they make pretty practical VMX bikes given the engine is more or less still in production so you can buy as many engine spares as you need.