I've been talking to a few fast racers who I built sl23 wheelsets for over the winter. They've all sold there tubulars and are using the sl23s for racing and training. With either a 23mm corsa cx with latex tubes, or a schwalbe one 700x23 tubeless tire, the speed they are getting are good enough for 1/2 races. 1350 gram wheelset, no glue, just ride them....ride them all the time. One of them admits that 404s are faster, but not enough to deal with the glue, the cost of the tubular tires, and the thought of having to replace a $900 rim if disaster strikes...sl23 replacement cost is $70.
I've ridden these wheels quite a bit this year. I had a set with cx-rays and industry nine hubs($675) and they were fantastic. They sold the 2nd I let someone borrow a set for a fast training ride. The cheapest set is $400, with bikehubstore 280 gram hubset and sapim laser spokes. If you are fat, you should consider doing race spokes on the back wheel, 40 grams more, but will put up with your weight.
All black non machined rims are available for you disc brake users(read losers) too.
For me, I'm sticking with the 404s I have until someone buys them. $1400 with a pair of 700x25mm corsa cx tires glued on, tires have 80 miles on them. 11speed, firecrest.
26" mountain bikes are making a comeback. This is 50% off, $1700.