There was a thread about this idea a while ago but I haven't yet seen anyone actually do it. My ERBE had some slop in the hexs so I figured since I had a spare set I might as well try cutting them down and seeing if it works. Heres what I did.
I cut the threads off the stock 17mm adapters leaving only the hex. I used a battery powered sawzall and the cut was actually pretty good. Pretty clean. Heres a pic of a newish set of hexs on the left and my cut hexs on the right:
The next step is to use some sort of cone file (or in my case a cone bit on a dremel) to clean up the cut end of the axle hole. If there are ANY burrs the hexs wont slide back over the stock axles. I learned this the hard way:
Then, of course, re-install the hex using the stock screw pin. Nothing special about this except the threaded end of the adapter is missing:
Lastly, install your wheels (with this mod you can use standard 17mm wheels OR traxxas style 17mm wheels) using the nut from the HPI 17mm hex set:
The results of this mod is nearly ZERO slop. After the install is done any looseness in the adapters is gone and the wheel is tight on the axle. Total cost, about $10 for the HPI 17mm hexs and nuts but you could probably get JUST the nuts for less if you look around online. The other benefit VS using the actual HPI hexs is there is no gap between the hex and the carrier bearing. Wit the HPI hexs you need to use shims. Total time for mod, about 20 minutes with some good power tools.
There are lots of other options out there. But since anyone wanting these type of results likely already has a worn out set of stock 17mm adapters you might as well try it. You have nothing to loose.