You guys are on the right track. Froyo had no tracking software. I was on Froyo for aaages (got my DX on release, was on Eclair until we got the Froyo leak, then got a ROM based on the Froyo leak and ran it for about a year) and never had any issues with WIFI tether. When I eventually went to Gingerbread I SBF'd up (then promptly back down as I went to MIUI which at that point was on the Froyo kernel lol) and I never ran stock GB and/or non-2nd-init so I had no idea about this patch until I had to root my Mom's stock DX and tried running WIFI tether on GB and starting getting the Verizon popups.
Anyways, long story short, Froyo is free and clear without Wugs. They have the same files, but GB had some radio updates in the NV items and they also integrated some of the tracking firmware into the settings which b0rked up everything as you couldn't remove it as it was the settings. You can remove the additional tracking items (I probably would to be safe) but the patch itself is not necessary, as it will work even with the tracking packages that are on Froyo.