[The HACK]

At 48K miles your front control arm bushings are likely shot, whether they look it or not. Plus the car is likely over 7 years old now, time to replace it, whether that is the source of your noise or not. Could very well be the source of your ride degradation (besides the fact that the dampers are likely shot as well, or at least, far less effective than when they're new).

Motor-mount related issues should show up while idling at a light as a vibration that can be felt throughout the chassis, but again, if you haven't done so already, the bolts on the mount should be replaced.

I would replace those two parts above first and foremost because they're probably due anyway. If that doesn't solve the issue, it's likely that a bolt attaching the triangulated strut brace to the firewall may have come loose. It's a pretty common problem on earlier Z4 Coupes but is suppose to have been fixed for MY2007. Inspect the bolts at the firewall and at the strut side, make sure they're properly tighten with zero slack.

If the above STILL did not solve your problem, then it's likely something has worn out in the camber plate. It shouldn't, but it's not out of the realm of possibility. If you still have your stock strut hats, swap them back and see if the noise goes away. If it does, then you've isolated your culprit.

The LAST possibility I would check, is check your sway-bar mount. It's not common, but it's a failure point in the E46 chassis and it is also a weak point on the E85/E86. But typically I see this sort of failure on cars with larger aftermarket sway-bars or cars track HEAVILY or both. The twisting forces of the bar literally rips the bolt out of the mount.