In all fairness...and to lend some balance to this prop bashing thread....I have to say that I regularly use Dynathrust props, in the 18" to 22" range, on all of my giant scale planes. They are strong, and they are cost effective. They may not yield the same high performance figures as the much more costly composite props, but then they don't break the bank either. If you are flying IMAC, pattern, 3D, or another venue requiring the very highest performance that modern technology has to offer....spend the dough to get what you think you need. However, in the real world of sport flying, or warbirds, where maximum performance is not a primary requirement...the Dynathrust props are tough, reliable, they perform well, and they are easily within the price range of most modelers. Additionally, I prefer them to the much more delicate wood props which are priced similarly.
In terms of reliability in normal service...I have never had a Dynathrust prop fail...and I have never seen one fail...and I see huge numbers of them at the many Big-Bird and warbird events that I frequent every year. I would suspect that props that come apart in flight, do so as a result of some unfortunate previous, abusive incident....such as tree and shrubbery landings...lawn-dart landings, nose-overs into the dirt, improperly reamed/drilled prop shaft holes, spinners cutting into the prop, etc etc. And if you do manage to break one....yes, the remaining pieces do make a damm fine paint stirrer. Manufacturers these days are quite sensitive to liability issues, and so they go to great lengths to assure that their product...especially a propellor...stays together! I hope you find this information helpful, and a bit reassuring.
Happy landings.
Jim