Straight-forward to Virtualise with XEN or KVM on IBM Server System x3650 M4 791562G?

I want to built a virtualised Server Environment using XEN or KVM. The virtual machines should be purely debian systems - so XEN or KVM should be a sane choice. Now while buying servers, I am confronted with the fact, that the vendors obviously only support commercial solution. I think, on a good server, one should be able to install uncommercial software as well - but of course sometimes systems have hardware, that requires drivers, that are not found in the OS Community.

So I am asked the question: Is it straight-forward to use Debian with IBM Server System x3650 M4 791562G with Debian - or even virtualising the IBM Server System x3650 M4 791562G using XEN or KVM.

I am sure there will always be a way to achieve this goal - but this way might have a high milage - so I am not asking, whether this is theoretical possible, but whether this should be straight-forward and practically easy to do, no major headaches to be expected.

KVM can definitely work. Look at Red Hat's RHEV (expensive), Proxmox (free), oVirt (free).

Despite that, VMWare ESXi is the most straightforward and least troublesome platform (momentum and mindshare). I wouldn't be concerned about it being open-source or not, since the hardware-compatibility is well-documented and there's a very large user base. I've seen people do amazing and creative things with the free version before eventually graduating to the paid product.