so in your opinion, is it ever a *good* idea to shoot angled down on the cb on any break shot? if so, why?
Not if you're breaking hard. First there's the high probability of jumping the cb off the table. Second you can lose precious speed and force as the cb bounces it's way to the pack. I recommend that if you do angle down your cue, you experiment and do it very slightly.
I am not an instructor, and I will not pretend to have the experience Fran does. However as someone who's broken a gajillion racks over the decades I may offer some insight as well.
The key to breaking with the hop is exactly what Fran is suggesting to do. The angle to which you hit the CB with your cue is fairly slight (required angle is power dependant). Keep in mind the goal here. The idea is to have the CB in the air when it strikes the head ball in the rack. How much 'hop' you will generate will be a combination of the speed to which the CB is travelling and the how much higher the CB is relative to the OB. The amount of bounce the CB will have is also relative to the power of your stroke.
Now my break shot is relatively weak in power when compared to other players my speed. It's still stronger than most (most = everyone that plays pool), but weaker than the guys I compete against or above my speed. I say that because I really don't have an issue with launching the CB off the table. You can equate that to either a lack of power or my ability to hit the head ball squarely. I have no issues generating a hopping break with my bridge hand on the table. Again it's all about cue angle relative to power. Do produce this type of break bridging off the long rail I need to place the CB near the rail so I can generate enough striking angle. Unfortunately, this shortens my stroke a good deal, so I suffer from a lack of power.
While you do indeed lose the transmission of CB power into the rack if the CB is in the air, (the hopping action is ~equal to that loss), I would struggle to believe that the amount of lost power/speed while the CB is bouncing to the rack is more than inconsquential. Certainly a loss, but nothing to batt an eye at imo.