OEM shock is linear, it is the linkage that is progressive.

Progressive springs make less sense on the front, but at the back they can be worthwhile (which is why the rear linkage is progressive in the first place), as they increase the rear end's progressiveness (is that a word!?) Particularly useful if you are often switching/changing the load on the rear suspension, say from solo to solo+pillion, or solo to solo+luggage. However, if you only ride "one style" then a linear is probably better suited, setup for exactly that type of riding/load.

They are more difficult to setup the sag though as Pete says, but they are more adaptable so less messing about with preload is required for changing loads.

I can vouch for Yacugar/Hyperpro shocks - had one for a couple of years now and I'm very pleased with it. The Wilbers is a good unit too.

As for the bushes in the forks, I'd say if they aren't worn and there's no play, then leave 'em alone. Regular fork oil changes are the saviour of bushes; if you remove all the metal particles that wear off bushes regularly, then over time you'll stop them causing further fork internal wear.

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