The retailers I talked to said that many of the cwrs slazengers they sold came back within 2 seasons, ie the faces having collapsed, or cracks having merged with the bores etc.
To help people picture the weight saving think of it like a simple volume question from your school days:
If you picture a 1/2" or 5/8" hole spanning the length of your blade and then halve it lengthways and magically juxtapose the 2 portions into the back faces of your bat either side of the spine in place of the concaves the weight saved amounts to bugger all. What ever benefit cwrs gives to a bat by way of very small weight savings it takes away in structural integrity and then some. What exacerbates the situation even further is that many of them arent even bored straight, curtesy of a wandering arbour the actual path often strays off centre in the bat where its 'shallower' and the wood cover isnt as great and where you can least afford weaknesses. And many try to get get 2 bites of the cherry by concaving in addition to cwr in their bats, even further lessening the 'wood cover' throught the side walls (and they dont seem content to have just a little concaving with their cwr either). It depends on the individual manufacturers methods:
+Some drill from just above the toe (which starts roughly accurate) right through the length of the cleft into the splice which isnt a nice thought at the best of times being a vunerable area, but then any run-out and the danger multiplies exponentially.
+Others drill 'stopped' bores to avoid the more vunerable areas but for less of a weight saving.
So if you were to picture the 2 halves of the bore again and then flaten and stretch the radiuses out into 'ever so slight concaves' (which is what they eventuate to) so that the same amount of volume is displaced - you have the same amount of weight reduction for 'virtually' no speakable weakening of the bats cross section.
As you can see it opens a massive can of worms, and thats not all of it
Hope that makes sense to you Norbair