"Progressive" is a term, referring to a graduated spring rate... giving some soft travel and some stiffer...
It is also a brand name... (they don't own the concept,... just the name)...
You can see shocks with graduated springs... they are springs that start with narrow spacing and increase to wider...
I personally think Progressive brand are excellent, but overpriced...
Most shocks now, are progressive... it's just a matter of finding the right firmness for your bike and weight,... and choosing how much travel you want...
More travel is always better... within the limits of swingarm design (12.5" on our Savages)... but, many don't like the look...
Then there is spring rate... (figure your average load,.. and err on the lighter side)... the more travel you use, the more you take advantage of the extra travel...
More length is better,.. less rate is better... (as long as it supports your load)...
I have Intruder shocks...12.25"... they come from a heavier bike, so I expected them to be firm... they aren't... I have them set on the firmest position, and I am 145lbs...(must be the angle of the mounting)...
I do love them... but I wouldn't recommend for regular two-up riding...
... but,.. don't over buy the spring rate... you are killing the advantage if you aren't using the full travel most of the time...
JMHO...

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