I posted this over at VS from Brandon at BHS, and it matches what was posted above...
My test builder had the following comments about the TB415, which are more informed than any I could give you. Take a look. It was designed with cross and wider tires in mind. In many ways, it's a Major Tom clone.
"I did take a look at your new 23 alloy tubular specifically to see how well a 25mm road tubular fits on the rim. The other night I dry mounted a 25mm Tufo road tubular on the rim to see if it would work as a road rim.
Your wide alloy tubular rim is extremely similar in every respect to the Velocity Major Tom which I have used building alot of cross wheels. However, there are some subtle differences in the shape of the tire bed. The outer (convex) edge of your 23 tubular rim seem to have a slightly larger radius (more rounded), and the concave rim bed seems to have a slightly smaller radius. The vertical depth of the rim bed at center seems to be the same. The net result is that a 25mm Tufo tubular road tire seems to fit OK whereas with the Velocity Major Tom, there is a tiny wedge of space between the rim bed at the outer portions of the rim. The difference is quite subtle but from my initial inspection it seems that your rim will work with a 25mm tire whereas the narrowest I would go with a Major Tom is 27mm tire. I’m quite sure a 23mm would not fit well on your rim a 24mm would be questionable.
All of the Wheels I've built with Maj. Toms have been for cross and have been built either 24 or 28 front and 32 rear and have been plenty strong. However, Toms are not as stiff as the Hed Adennes wide tubulars which I've used for lower spoke count alloy tubulars. I've never built lower spoke count with Toms. I would expect your rim to have similar strength/stiffness to Maj. Tom. Not clear whether the rim is strong enough for a 20 front/24 rear for cyclecross or heavy rider. My gut feeling is that using wide front hubs and 8-16 lacing in rear, a 20-24 build should be plenty stiff for small to medium size riders and perhaps a heavier rider such as myself.
Assuming they are stiff enough for a 24h rear build, You might consider getting some (or all) of the 24 H rims in the next batch center drilled which works better for 8-16."