09-11 shock shortening? Anyone tried?

I have a 2010 FX450, I like it a lot but its really crap in long off road type ruts, It tries to climb out of the ruts all the time and if you got a bit of pace on and you slow it shakes its head really bad to the point of crashing. To counter that the bike will turn on a six pence, it will under cut and hold a tight line on a MX track better than anything, you can turn inside anyone. Sag is set at 105 currently, I have the 22 offset 3x clamp, springs etc are all set and good, bars in usual 4 stroke position back hole facing forwards on clamps etc.... Oh and I can ride.

Also watching 4T Bergs being ridden by the world class riders always look high at the back, Were it an Aluminium sub frame I would be tempted to cut out 5 mil, and not because I cant reach the floor I am 6 ft4. That is not an option so shortening he shock is the only way?

What if the rear shock was shortened slightly, Only a couple of Mil? , transfer a bit of weight to the rear and would help with the diving in the ruts, headshake and diving into big bermed corners?

What you all think? Well the qualified ones

The factory were using 24mil offset in 09 on the EWC bikes.

OK I described it wrong, Its not really headshake, It crabs on the sides of the ruts and normally on other bikes you can correct it with a bit of a lean or a dab but on the Berg it just seems to make it worse. It gets to a point where you have to almost make a complete stop and set off again. Its good whilst your accelerating but once you try to slow down... it gets sketchy.

Going into a corner hard with a big soft berm the front seems to dive when riding but when you watch the bike its like rear is coming up more than normal (other brand) rather than the fork diving,

The 4 mil thing, how much did it drop the rear of the bike?

I've done the 6 days a few times also and finished everytime, I am just older, fatter and slower now....