Good to see a fellow mythtv user attempt to take the plunge.
I would check out the archive section of these forums. There are a lot of experiences that the guys using pluto have documented that may be helpful. I plan on following the same path and I am reluctant to kill my beloved mythbox. I have found several posts in the archive that talk about using a pure myth frontend with the linux mce/pluto "core" as a backend or using your current myth setup as a slave backend. This may be the intermediate step we are looking for.