Pretty much the same behavior and abilities. Slightly different frequencies and therefore different coils. Personally I think the overload thing is being overblown. I only thought that after using the Racer. To me it just isn't a big problem. I can raise a coil a couple of inches or just run with the Gain down a bit and not lose much depth. The way these machines mix the audio is pretty cool. Not just a low or high tone but a blending to let the operator make the call. The small coil is the killer in heavy trash like old homes and ghost towns. The Fors Pro pack is a heck of a deal since you get 3 coils versus the Pro pack Racer gets you 2 coils. Either way both are bargains. In my mind it comes down to which machine you might prefer for the ergonomics, or if you really need the big coil then the Fors is a probably a better deal. But like someone said, big coils are for finding big stuff. Probably a relic hunt would be the ticket for that big coil. I think some may have been used in the digging Virginia hunt this year but I haven't seen any feedback. There are reports they work great in the nasty coil in that area. My soil typically comes out around 80 on the Racer or even when I had my Gold Bug Pro. All this said I am still learning mine and only have about 10 hours on it. But I like it a lot.
Just for reference I have owned a V3i, Etrac, CTX3030 and Deus. I've been up and down the features and prices of detectors and am really just trying to find something light, simple and effective. I think the Racer just might finally fill that slot.