To clear a few things up, if your mechanic is removing bearings from cups, then you will likely have an issue.
Here a simple breakdown. There are really only 3 areas an integrated BB like you have can creak...only 2 with BB30 btw:
1. Outside of bushing to inside of frame shell
2. Outside of bearing to inside of bushing
3. Improper crank preload.
It really is that simple. Press in bearings into plastic cups can easily cause a problem. So you want to eliminate no.2 above by having the outside of the bearing bonded to the inside of the larger bushing. Yu want integrated bearing into cups as shown here which is the correct BB for your bike:
Rotorbike
Available in either steel or ceramic bearings. Save your money and get steel but if you want the best, then get ceramic...little difference.
If you note in the picture, the bearing is bonded to the larger OD bushing. That is what you want. This sub assembly won't creak.
So all you need your mechanic to do is buy a computer and following the following link:
http://bbright.net/BBrightTM-Press-Fit-Instructions.pdf
This shows the correct Loctite to install the correct BB. Be sure your mechanic knows what clean means. The BB shell has to be immaculate and then use a primer to get the Loctite to stick.
The crank should be installed immediately before the Loctite sets up to ensure alignment of bearing bores.
Now your mechanic has to figure out how to adjust the mechanical preload of your Rotor 3D+ crank. It isn't hard but maybe it escapes him.
People that struggle with these BB's miss one of more of the above steps.
HTH