I'm thinking about switching from my trusted RB450G to RB1100AHx2 but I need MetaRouter or any other yet unrevealed virtualization solution for missing OpenVPN features. Don't feel like having this part split to another piece of hardware.
It is possible, today, to run MetaROUTER on RB1100AHx2, as long as you are okay with an unsupported solution, are willing to put in a little effort, and are okay with using the AHx2 as if it is an AH instead (sacrifice dual-core functionality for single-core...even with just 1 core, the router is plenty fast: after all, the single-core AH was no slouch, and way faster than a 450G); see here: http://forum.mikrotik.com/viewtopic.php?f=15&t=77451
(I actually need to update that article, because MikroTik changed the RouterOS package format some in 6.14, so my original instructions for extracting the kernel file from the NPK stopped working after 6.13.)
However, you probably don't want to. There are stability issues present in the PowerPC version of MetaROUTER that affect the entire RB1000-series (1000, 1100, 1100AH, 1100AHx2) that are still being worked through. Supposedly the RB800 is stable, although I haven't tested it myself. If you do end up wanting to try this, you either need to use 6.20 or wait for 6.23 to be released. (Alternatively, you could try your luck with my trick on an RB850Gx2, which is the same form factor as a 450G and not much more expensive. I have had good luck with it in my tests and no stability issues so far.)