The success I have had with the 20/24 spokeFulcrum wheels that came on my Roubaix have opened my eyes to more adventurous wheel designs for my road bikes and I have also had no problems with the 28 spoke front wheel on my Stumpjumper. That said, I am building a set of wheels right in line with Barrettscv's formula for my Salsa Casseroll which I often ride fairly fast on dirt roads with wide tires. I am going with Velocity A23 rims, Shimano Tiagra hubs and 32 Sapim Race double butted spokes (similar to DT Champion) front and rear.

I am re-purposing the similar wheels with Mavic CXP-33 rims and Ultegra hubs to my son's new bike and I figure the wider A23 rims will provide a better profile for the 37mm Conti Contact tires I'm running on the Salsa.