I've been hesitating to ask for anything new with erode because there are already so many settings at our disposal and I'd be lying if I said I've exhausted all of those options; however, I think we are to the point now where perhaps some additions/improvements may be possible.
Still facing quite a few of the same problems, and hopefully these solutions will help:
1) Feels like you're riding "on the dirt" versus in the dirt
2) It's very hard to establish a 2nd or third alternative line
3) Erode is tough to see, the higher it is turned up (deeper) the easier it is to see of course, but that comes with it's own problems.
4) Radius for ruts versus bumps varies greatly, but we're locked into 1 (using different tilemaps is often not an option due to where you start turning, the transition, and allowing multiple lines) - more on this below.
5) In-ability to create a rut that is "too deep" or slower when it gets deeper (#1 priority to fix right now IMO)
In no particular order:
A) Displaced (built up) dirt versus "dug in" lines - would it be possible to differentiate a "hardness" of these? Currently, the top soil feels like it has the same effect on the physics as more dug in stuff causing a cheese grater type effect outside of main lines where in the early laps riders are crossing at different angles before a main groove is established (at least when erode limits are turned up enough to cut through the top layer quickly).
B) Rut shapes -

Red - Currently, these are the rut shapes we are getting on anything where you are turning when they are initially getting established. (think of this as a LEFT hand turn, the inside lower than the outside).
Green - Currently, this is what is happening to the ruts once erode limits are hit and it begins to try and "push out" the rut but can't build it up or dig down. This causes extremely jagged and sharp ruts that create a multitude of problems such as:
1) They are inconsistent and jagged
2) You are locked into the rut and can't cross over it at all
3) It's a wall ride
4) If you fall in it, you'll likely get a double or triple fall off
5) They don't form realistic chop or "blow out"
What I'd rather see is that "angle" stay locked and not keep digging out the bottom transition. We're working with what I already feel is low max angle (.35 lately). I'd also like to see if somehow the inside (left part of rut in this case) would actually build up. I know unrealistic, but it would be a way to start to make the ruts more challenging and "deeper" feeling which may encourage guys to find a new line.
I understand why this is happening, but I don't feel like we're getting enough dig down versus the amount of build up even with running large depth and inner-depth settings and very low displacement settings.
C) Fluff layer -
While using the erode limits, I am able to erode the top quickly with success, I still have a large desire for a top "fluff layer". Problem is, once this is gone through at any angle it is hard as a rock. I'd like this layer to erode through quickly, carry increased drag (and side to side traction...think of laying over in freshly tilled dirt or even sand, you push a lot of dirt so it holds you but also sucks your power). Now this is easy to ride over until it starts to get "packed". Right now, we don't have any difference consistency in dirt (packed versus fluff)
This would help visuals a ton without creating a cheese grater.
This would also help develop new lines because of the visuals as well as the increased "hold" when trying to power out a new line (drive in deeper, it helps you slow down, lay over harder, it has some hold) and also would help with the opening laps not feeling so slippy.
The increased drag and soft fluff versus packed dirt would also make it feel much more like riding "in" the dirt.
D) Radius for bumps versus ruts -
Currently, when using a smaller radius needed for ruts, the bumps are tougher to see and just feel very chattery as they are fine and close together like a washboard. If you go larger with the radius to create more rounded and spaced out bumps that work much nicer, the ruts get very big and wide like berms. They also take up so much space in teh turn that it is very difficult to have a second line form. The smaller ruts allow 2 or 3 lines to be fairly close together of course until one gets giant (see "B") and dominant
E) Straight ruts/jump faces
If you aren't turning, whether you're accelerating or braking, we aren't getting much for lines. Jump faces are all around almost always a no-go for ruts as they just turn into a pile of cottage cheese. Again, I feel like the ability to "dig in" is not enough while build up is too much across the board.
F) On throttle dig -
Again, running a mutiplier on "slip" and I still really don't see a good effect from the back tire digging while accelerating. I think during acceleration we need it turned up quite massively to allow getting on the throttle to dig alot more. This would help with quite a bit I feel -
1) Ruts leaving turns still don't form as well as entering which seems backwards.
2) acceleration bumps would be formed where riders are getting back on the throttle.
3) New lines would be easier to form on exit if they weren't so dominant entering the turns

^^^ MXS = green and IRL = blue
I know I have quite a bit more, but this is obviously quite a bit. I'm still working hard on my side to develop what we're given, but hopefully we can get some additional support from your side to make further improvements as well.