can the rear shock on a 2007 xtx be adjusted firmer or softer. if so what is the result? and is it worth doing?

It has no rebound or comp adjustment only preload the spring.

http://www.ebay.com/sch/i.html?_nkw=...at=0&_from=R40

http://www.ebay.com/sch/i.html?_nkw=...at=0&_from=R40

or some other brands?

OTR do Wilbers & Ohlins shocks for the XT660....
Don't know about the XTX I have a XTR.. but that long C spanner "hooky looking one" in the tool bag is for
adjusting the rear shock spring pre-load....

__________________
Harley Davidson..
The easyest way to turn gasoline into noise with out the side efect of horse power...

You can tighten it up with C spanner in toolkit - I think the idea is to tighten if you are a heavy ******, or loosen if you are a light weight.... I adjusted mine up 1 notch, but the C spanner is made of Yamaha-monkey-metal (AKA cheese) & the handle is so short I couldn't get enough leverage to go to maximum stiffness without breaking my hands/skinning my knuckles..... Still, it seems a reasonable compromise for B road commuting.

Haha I adjusted mine today and exactly the same thing happened

Got to middle adjustment fine

Tried to get to max and no way would it go, so I stuck the square ended bar in the square hole at the end of the c spanner and the spanner just snapped.

Crap monkey metal indeed.

So I'll be leaving mine at middle setting till I get a better c spanner.