Seatpost 10mm layback seat 3/4 back. Tried with seat all the way foward/back (also tried with 20 mm post)

If you feel that the TT's too long, ditch the layback posts. Stick an in-line post on there and get more weight over the front.

This seems odd to me. I'm 5' 9" and went for the Medium when I bought my Soul (equivalent 17.5" I think) as I was on the border for Small/Med.

I've got a post with 20mm layback with the saddle smack in the middle of the clamp, a 90mm stem, low rise 660mm wide bars and it feels great. I've got a Revelation on it and at 100mm travel it climbs great and is sweet in the twisty stuff and at 130mm it descends really well. I've rarely ridden a bike that feels as well balanced.

rather than try random bits of kit, I follow some rules on bike fit which work for me. They are: -

Sat in the middle of the saddle, a plumb line from your knee cap should hit the pedal axle with the cranks horizontal with the ground. Adjust the fore/aft saddle adjustment to suit.

Sat on the saddle with the crank at it's lowest point, the heel of your extended leg should just reach the pedal with your leg straight. Adjust saddle height to suit.

Once the saddle position is sorted, touch the nose of the saddle to your elbow and extend your arm towards the stem. Proportionally, your finger tips should be on or around the top of the steerer. If it goes past the steerer, then I'd stick a slightly longer stem on, if it comes short of the steerer I'd try a shorter one. My rule of thumb is that my arm from elbow to finger tip + 80mm is about right for the saddle nose to the stem/bar clamp. This isn't an exact science of course.

Oh, and I use 175mm cranks.

The Soul is designed around a sweet spot of 115mm travel forks to take the 100mm - 130mm range comfortably. If you're outside this range, it will feel weird.

The frame is the right size for you. If you're sure you've got the fit right on the other kit and it still doesn't ride to your liking then it's probably just a personal preference thing. I admit that some people don't get on with the 'long travel hardtail' type bike and I note that you've been riding various bikes of various types for some years. It may be that you are just used to more traditional geometry.

Sat in the middle of the saddle, a plumb line from your knee cap should hit the pedal axle with the cranks horizontal with the ground. Adjust the fore/aft saddle adjustment to suit.

Personally I ignore this one - I just move the seat fore and aft until the reach to the bars feels right ;-)

I have tried lots of the things mentioned here (over the last year or so) and though each thing does make a difference, it all still doesn't feel right. I do test each change individually.

A few days ago moved my seat foward to match the plumb line thing, reach was right with 70 stem. Felt better, but still felt a lot worse than any crazy hodge podge config I have on the Scale.

Maybe i am just used to more traditional geometry. Or since this is the only 'long travel HT' I've ridden maybe all bikes in this style feel like this and I should just lower my expectations.

In desparation, even tried 100mm forks with 2.1 tyre up front and 1.3 / 1.5 / 1.9 tyre at the back to try and simulate a 115mm fork head angle. - Still no good.

Felt very much like I was sitting 'on' the bike rather than 'in' it

Yeah, it does feel a bit like that. Taking a longer fork means that the front of the bike rides higher (obviously) and the BB is also a touch higher, making the ride feel a bit top heavy. The seat angle tends to be a tad steeper too to push you on to the fork a bit too. You do get used to it though and once you get the hang of riding that bit more aggressively with your weight forward it all kind of makes sense.

Trade it in for a Soda :-)

http://www.donsgallery.fotopic.net/p40243266.html

...but not a toy one......

Shame it's not the medium cos my bruv would have bitten your arm off for a used one LOL. A serious suggestion would be if you live anywhere near Sherwood Pines (Nottingham) there's one of AQR's skills days coming up on the 9th June. There are usually Cotic riders there who can help you out. The Great MTB God Cy himself has even been know to attend.
Best of Luck, Timmy :-)

mmmm, odd, I have a soul too and found that at 100mm the steering was too twitchy (80mm stem) and at 130mm it became a bit barge like. I found it all came together somewhere in between.

I found the ride rather confidence inspiring, so much so that on my first ride I ended up havig a big high speed crash 'cos after 30mins of riding I felt like I could take on the world...

We're all different of course, but just for the record - this works for me. I'm just under 5'10".

I ride a medium with a 90mm stem with RF Deus low risers. I use the current RaceFace Deus seatpost (which I think has half inch lay-back) and WTB Pure saddle. I pop my elbow on the saddle nose and the end of my middle finger in the centre of the headset for the fore/aft adjusment. I have the saddle about flat and certainly NOT up. I set my saddle height so I'm right on 'tippy-toes' with just the points of my shoes touching the ground. This is comfy for me.