You're exactly on point about my thoughts. It is all well and good to get a bit of gain, but at what cost? I mean that is why I did the ITB kit the way I did, I wanted a car that drove better overall.
I had a look at page 12 - are you running 11.4mm of lift with the OEM pistons?
The problem with cams is that there is no real academic way to predict the engine behaviour. There are good modelling and simulation tools these days but in reality they're an indication at best. As best I can tell, the OEM and aftermarket cams that are designed for the road are actually all relatively long duration, I stand by what I thought when I initially started this thread that BMW intentionally detuned this engine.
I think what catcams are doing with their sport cams is that they reduce the total duration on the exhaust, and increase it on the intake, but the ramp is increased so it has the same 'effective duration @1mm'. In that case they're making the cams more aggressive, but with less overlap so they're preserving idle and low end. If this is the case, the improvement comes mostly from higher lift from the intake cam. After speaking to cat cams, they have another set of cams they sell inbetween the sport and track cams, and the data sheet for is the only one of their street cams that has more overlap than the OEM cams, so I think that will be the one that takes off when it revs up with a bit of trade off in the low end since it is the only one that will crossflow more than the OEM. Because the OEM cam gears are slotted you could in theory run a couple of different combinations of cams and then change the timing anyway to change your torque curve. So again, I wish I could print some money like the reserve banks of the world and just do some testing!
I've asked catcams for a few more details about their cam setups, see if they have any modelling or results they can share, and then I'll make a decision. I'm leaning towards the more aggressive intake cam, and then clocking the OEM exhaust until I'm at a point where I'm happy with the amount of idle quality I'm sacrificing for the move in the power curve.
