IMHO...
- staged filtration is the way to go with courser filtering first then finer.
- 10 mics more than adequate for that engine as final filter
- Vacuum gages a must for all filters (at $20-30 each)
- spin on buck filters preferable to Racors although I have had both
Vac gages will not only save money on wasted filter changes but will also allow you to plan changes that do not affect trips and help diagnose potential engine issues.
I have had plenty of Racor 500'sw and 900's but find they have a few issues - hard to replace, prone to air leaks, lower filtration areas, costly housings, awkward available vac gages, and relatively costly filter cartridges.
Some folks believe that a 10 micron filter stops all particles above 10 micron and acts like a gridded 'screen'. Filters actually pass a range of sizes called out in their beta ratings and are best used in their designated 'ranges' with courser filters working on the fuel first. You will achieve a better filtration on the fuel and a filter life of 3-5 times the fuel volume when properly staged filtration is used with vac gages.
If the goal was only to filter down to the smallest particle size why would we stop at 2 mics and not go to sub micron filtration?
Here is the link again to pics and examples of how to do it for the long haul and for potentially poor fuel and higher use.....
Fuel Systems & Filtration - Seaboard Marine