TP - its a low maintenance hub, which is why builders / manufactures like to recommend them. I think I'd argue there is a healthy profit built into the RRP as well if you were buying in bulk. The internals are good & sealing is excellent which makes it a great trainer, but it is based on certain compromises.
If its left to the builders choice - would they recommend something that might come back with problems - say like the creaking tune hubs of old or plastic internalled extralites, or recommend something that is known to have proven reliability - albeit that it does so in a slightly compromised fashion?
FWIW if it was for training purposes & I was talking over a custom build, I'd suggest the client look at the 350s hub over the 240s - certainly on the rear hub. Its got good build standards, just with heavier parts. If its a trainer wheelset where weight & out & out performance is less of a priority you'd get a durable hub but without the huge premium.
Also for some extra background on hubs generally which might be of assistance to the OP; http://fairwheelbikes.com/forum/viewtopic.php?f=65&t=6940
FWB - Hubs review- 240s rear;
The 240 hub was included in this review because it is such a dominant force in the wheel industry. So many companies use it as their hub that it has become a sort of "standard" so I thought it would be nice to see how it actually compares to the other boutique stuff. It's not the heaviest, there are 3 others that are heavier, but all of them have much higher static loads, and all of them have much larger bracing angles resulting in a much stiffer/stronger wheel. The DT is competitively priced falling right in the middle and has a very middle of the road static load capacity. It has the smallest DS bracing angle of all the hubs tested, including other interchangeable bodied hubs but at least this provides a decent tension difference of 49%. The DT uses a ratchet drive instead of a standard pawl system, and the ratchet systems seems to have a very good track record for reliability. The hub is easy to overhaul and needs special tools only to remove the splined half of the ratchet system in the body. There are two things about this hub that are very appealing to me. I like that you can easily change from Shimano to Campag and back again in only a couple of moments, of course this comes at the noted reduction in flange spacing. My biggest draw to this hub is the way it's become completely widespread in the industry. This is good for anyone who needs service or parts. You can walk into your local shop and there's a good chance they'll have whatever parts and knowledge are needed to maintain it. Customer service with DT isn't the greatest or the quickest, but luckily as a consumer there won't be many opportunities for you to have to deal with them. The noise in this hub is a bit on the loud side, but not overly so and can be quieted with some lube. On a 1-10 scale for noise with 1 being a silent clutch and 10 being a Tune Mag90, I'd say the DT is a 7 in noise level.
Ron: Definitely a decent reliable hub and at a good weight as well. The bearings are large enough and they rarely need overhauling. Lubing the freehub mechanism is a very easy job. The biggest negative is the less than optimum flange offset on both sides. Plus the price has been creeping up. I've used a lot of these in the past, but doubt I will very often in the future now that the Alchemy, C-4, and Chris King hubs are available. DT sells these pretty cheap for OEM applications, which reduces their value for customs in my opinion.