Firstly NEVER buy a hope!!! They are 1 Loud & 2 Crap!
You have one of the best hubs around in my opinion for durability vs weight, the issue you have is the same one I had and your LBS may be correct. The way I over come it was to switch to the RWS Skewer, gives loads more tension than a standard QR. Another tip which will help is to release the chain tention when fitting i.e. place the wheel in the drop outs, remove the chain from the front rings, centre the wheel and tighten the QR, replace chain onto front rings. This ensures the wheel is dead straight in the dropouts as sometimes there can be side loading from the chain tension.
The only other thing it may be is the bearings, which will mean you will have to make a tool for the inner female star ratchet removal (Unless you have already bought one). The cheapest way to get hold of these tools is to buy a spare star ratchet for £12 and weld it on to a M20 Bolt. Change all the bearings and it'll be sorted.
