Here is something everyone can try. Stand over your bike, hold the front brake, look over the handlebars and at the front tire and leading edge of the front fender. Compress the forks quicky while looking at the relationship between the front tire and the fender. After you try this, please reply with what you observe. Those with a brace should see something different than those without, as should someone with a dual disc bike.

I haven't tried it as mine is all disassembled but I believe what you will see is that if the brake is on the left, the fender will apear to go forward and to the left as the wheel twists back and to the right.  It is a demonstration of the axle relationship to the bike twisting due to fork flex.

So.....   about 1/4 inch of tire to fender movement....  but .....  is this fork twist or bearing slop.

Brace will solve twist  but not slop.

I've been debating the brace for awhile.  Was going to get one, but when I took my wheel off to get a new front tire I realized that the axle holds the two fork tubes in place and it goes into fat chunks of aluminum so there should be almost not tube to tube twist.    

So, to test if it's twist or slop, I added a thrid reference point (see below).  And,  found that the fender & upper forks do not move, so there is very little twist, if any. (my eyes aren't perfect....)  Was thinking that the duct tape might be moving to damper effect but still would see movements because of lenght of wire.

Bearings?  (Greg.... you said this before....) .  Tighten the axle??..  steel & aluminum expand at different rates, so I guess it should be checked & re-torqued (to spec) every once and awhile.

The axle is mild steel & not really all that massive. It's not impossible to believe it could be flexing under the torsion load. The brace at the top of the lower fork tubes would protect it from that load. I couldnt quite "get my head around" the way the forks were flexing for a while, but with the wire & all, after some hard mental imaging, I finally got it. The wheel is pressed back, driiving the left fork back, the axle is the only element transferring the force to the right fork tube & that fork tube doesnt get all the poressure the left side gets, due to the axle being able to twist along its length, like a torsion bar. That, coupled with bearing clearances that are necessary plus the slop of wear. Maybe a brace doesnt completely eliminate it?It couldnt eliminat the slop part, as was previously noted, but the twist,  Owell, I just went out & messed with mine. I cant see any twist & it has a brace. Maybe I just cant get enough load on it at 2 MPH. I can say one thing for sure. I felt a difference in the "surefootedness" of the bike as soon as that brace went on. It allowee me to enjoy the performance the other mods gave it.

I know several folks have mentioned a fork brace with great enthusiasm, even over any other mods.
Any recomended brands or suppliers?