This Hakko is, I think, the same as the Deben DMP/Nite-Tec sold in the UK 9-13 years ago.
It can do the job, I came second in 2011 world champs in Italy and won a GP round with mine this summer. I've used it so long I'm just blind to its faults, knowing it so well probably makes me a bad judge of its qualities.
What I can say is that the ret is very precise, the turrets are great and (most importantly) the rangefinding is super stable, it really does seem the same at any temperature above 10-12 degrees. It will also focus right down to 8 yards without adaptors. Significantly lighter than a Big Nikko.
The glass could be better; I shoot on 20 x and at that power it's good but if I wanted to shoot at powers above 30 x I might look for a different scope.
If the price is reasonable then I'd recommend giving it a try; you will probably be able to get your money back by selling it on if things don't work out.
I really can't see how this is a worse scope than the Big Nikko but has always been far less popular, I think they were a bit more expensive; maybe it's as simple as that?
I've just put a Big BSA (MK1 Big Nikko) on my Walther, just for a change, so by next spring (if I actually get a chance to shoot) I should at least be in a position to judge the Hakko against its most obvious reference point.
I'd love to try one of these new mega scopes but I just don't have the spare cash!