yup
i have done that on my trail sled, i also use the bdx axle /wheels there with it. suprized more people dont use it ,, ( the bdx axle ) its a utility / value packed little mod for 70 $ , plus lose like 2 lbs or something on 07s-08s ,,
anyway back to the topic ,, check out your hyfax ,, where did they / are wearing ,, bet its right at the bend up in the rail. i did it on my flatland sled to keep those nubs from hitting the shock mount ( annoying vibration ). here is an old pic i had for last year , i didnt take it to illustrate the mod but you can see it there ,, but i added it to the boggie set ,, not just swapped them inside like you have. so its the axle wheels and the added idlers up front. also i mounted them with a mating OE bracket. i could see bdx marketing something like this , but i doubt the demand is there .. but who knows
benefit ? /shrug
i didnt do it to my mountain sled ,,i dont know if you would raise the chance of track stabbing without the outside boggies .. i kept my outside boggies on the trail sled and another note is its easier to slide around the garage floor.
nice skid btw, tell us what you think the pros an cons of doing it?