Have you really noticed a big difference? Last year my engine quit twice while we were out - both very inconvenient times. I'm looking at cleaning out my fuel tank but I would also consider replacing my existing Racor with this turbine model if it means no more stall-outs.
HUGE difference. I can not stress enough about how important a predictable engine is. It is truly the best upgrade I have done, as it provides peace of mind to me, knowing that when my high school and college kids take the boat out by themselves, that they can get back safety.
The r500 makes checking and changing filters easy and not messy. Not so with the old r20 metal can, so it was always ignored, and changed only once a year. The r500 gets checked every outing! I check the filter bowl for crud, and water before each flight, and if I do find anything, I drain it. Good to go. I am using 2 micron filters so I am filtering the fuel better than the secondary.
The filter is rated at 60GPH per hour, so my 2 diesels at full out will never pull more that 4 or 5 per hour.
Per your tank, yes you really do need to treat it and try to get all of the big crud out. I once had a complete clog shortly after buying the boat. The clog was not in the filter but at the 90 degree barbed fitting going into the old racor 20 metal can deal. I ended up pulling the fittings and used a coat hangar to clear it. I have seen growths that would resemble toilet paper in the tank. The other related thing is to make sure that your tank vents have a high loop in them to prevent rain, waves etc from getting in. Our 2004 came from the factory with no loop and could explain all of the water and growths that I found when we acquired it.
With a treated tank, and larger filter, I have not had any inconvenient stoppage. Like I said, best 300(labor not included) I have ever spent!