Could the RB 1100 AHx2 be used as Wan load balancing, actually I have two ISP connections?

That and much more.

Of course, with the proper settings. For example:

http://wiki.mikrotik.com/wiki/Manual:PCC

I have a shiny new 2011UAS-2HnD-IN that just replaced an older model. I have the new one working substantially as the old one did - with three WAN ports bound to a WAN-bridge. Only one WAN port will bind at a time. I have looked at a lot of the material out there and the question I have is this: Can I use PCC for load-sharing if the WAN connections have to use DHCP? In most of the documentation, it appears that the the WAN ports are on static IPs... Is this a requirement for it to work?

Thanks!

Thats a completely different question and should be posted in the main forum, not in this thread.

By the way, I can't tell you if it would work as I haven't used PCC myself yet.