You mentioned about the upgrade to the drums and chain/cables. Is this a good one to do?
As long as your current drums are working well, there is no reason to make the upgrade. It's expensive and would be best considered in conjunction with a needed replacement for a current drum or cable.
The kit that came for 2006 outback that reinforces the column. Should I use it on my 2008 revo? I think it would be harder to see cracks.
No. The factory incorporated all the "kit" changes already in your boat.
What do you mean by specialized epoxies formulated for polyethylene for reinforcing the cam columns?
There are two excellent epoxies for PE: One is 3M scotchweld DP 8010 and the other is Locktite3030. They are both industrial epoxies and may be found at an industrial supplier. You can check with the manufacturers for a nearby location. This is a "reinforced" cam column using DP 8010:
Not pretty, but it increases the strength substantially.
Note, there is another epoxy by West Systems called G-flex that is sometimes promoted for PE. It does not have the bonding strength for a job like this and should be avoided for any high strength PE work.
Have you actually measured the plastic in the column/mirage drive area?
I made a cut-away of my old Adventure drivewell area -- there is plenty of plastic. The nose of the drivewell area takes a tremendous repeated stress over time -- 7200 pulses per hour at a typical 60 cycles (120 strokes) per minute. All Hobie Mirage Drives incorporate a brass block embedded in a solid plastic base under the nose of the drivewell since '07 (in some cases earlier). This was done to better accommodate the Turbofins. There can be other reasons for cracks though due to abnormal manufacturing conditions relating to cooking time and temperature of the plastic. It is pretty rare, but possible. IMO, the best thing to do is use your boat the way you want to and if there is any abnormal defect it should show up well within the warranty period.
I wonder if my 2008 revo has the same amount of plastic as the newer models.
Yes, but it is rearranged a little bit. Gone are the plastic cam columns, screws and cams. These have been replaced with the Click N Go system, which I believe is stronger.
The clips seem to hold the drive tighter than my column knobs.
When you insert your Drive, you should tighten your cams good and (finger) tight so they lock up solidly. The Drive should rock a little fore and aft but be very solid side-to-side.