So an update on this, I got given a new pair of Metzeler Tourance tires from a friend of mine
I didn't really think much of them at first just looking at them but thought they were worth a try given the price, I put the front one on and took the bike for a ride and initially it was heaps quieter but as the back tire warmed up the howl started again, not quite as loud but still pissing me off
I came home and put the Tourance rear on and the difference is just amazing, the ride is just so much better now it's almost hard to describe
My driveway is around 500 metres long and loose gravel and while the new tires are slightly more skatey it's not that much different but on the gravel & bitumen roads around here the ride is so much better
I think the Motoz tires while they have a much more aggressive tread the compound is a lot harder and the difference in grip is marginal at best, at least while it's dry, The Metzelers will be pretty crap in the wet offroad I'm sure but I'm pretty happy with the handling & most importantly the road noise now
Oh and for you poor buggers in the US we are starting to hit summer temps here in Aus with predictions of over 100 degrees F in the next few days, I think in these conditions the new tires will be just fine but YMMV