Manfred,
The restrictions of disk and array placement will be found in the document below on Powerlink:
CX3-Series and CX-Series Storage Systems Disk and FLARE OE Matrix

Reading through it you will find that the limitation is not so much the enclosure type (as long as we are talking FC to FC enclosure) but the FLARE revision. Looking at the document you can even put old 10k FC2 73GB drives in a Cx3-80. I don't think the drives are specific to an arbitrated loop or point-to-point architecture; they are all dual-ported FC drives and the type of connection architecture is managed by the enclosures and the array.

I have upgraded drives in DAE enclosures with drives from DAE2P enclosures, which is going from a point-to-point to arbitrated loop infrastructure, with no errors.

If you remove a disk that is part of a RAID group, you are failing the disk in the RAID group and the RAID group will remain in a failed state until you replace a equal size or greater disk in the same slot. If you want to change the location of disks in the array, unbind the LUNs and destroy the RAID group before moving the disks around.

You can use this method to upgrade the disks in existing enclosures.

Hope that helps,
Aran