I'm actually using openSuse and looking for a change. Arch seems the way to go for me. Only one thing is holding me right now, since I'm not a too advanced linux user, I would like to know if Arch will automatically discover my 3 disks LVM in the installation process ... I really don't wan't to loose my data disks.
Partition yourself manually. Partition always if possible with the same tool! If it was Gparted, always with Gparted, if an other tool, always the same tool...
There is no reason to loose data because of a new installation!
If you look through the Beginners' Guide, you will see that the Arch install process is not like Suse's: you have complete control/responsibility for the install, with only some of the tasks, like installing software, automated.
So no, nothing is done "automagically"...
When you are in the install environement, just make your volumes available and proceed from there.