I strongly disagree with Phil Needham on this subject.  Phil has said in his presentations that he likes to see some soil being thrown out of the furrow by the row cleaners to get a nice "clean" strip. Accordingly, he likes the floating type that tend to dig more, and the spike-tooth type of wheel -- especially if they're Martin brand and orderered thru Phil  :-) 

I don't want to move soil during the seeding operation.  I don't even want to move much residue -- I *never* want to see more than 50% of the mulch being moved out of the row, and prefer to be down around 20 - 30% being moved (70%+ undisturbed in the row).  Heck, there are many long-term no-tillers who run without row cleaners of any type (no coulters either, and no strip-till), and they often get stands and yields that are the envy of the neighborhood (note that this is generally south of Interstate 80, roughly). 

A 'clean' strip is much too vulnerable to erosion, soil crusting (poor emergence), and nodal/brace roots not establishing in hot/dry soil.  Keep the mulch in place as much as possible!  

If you want more specifics on row cleaner adjustment, take a look at our DVD.  You can watch an excerpt for free, although you'll have to buy the DVD to see the part about row-cleaner selection and adjustment:

http://www.exapta.com/products/dvd.html

(Exapta *doesn't* sell row cleaners, btw.)