The MXO2 Mini does not add any Matrox codecs to any CS5 apps. The Mini with Max provides hardware acceleration for encoding to H264 and may add a Matrox codec for that. (Don't know as I only have the plain Mini.).

Without Cineform, one could use Adobe Media Encoder to convert AVCHD/mts files to, say, Microsoft AVI or to a plain MPEG2 or maybe to MXF. I imagine that MPEG2 would be like editing HDV after conversion.

I've never tried this for editing files since I have Cineform NeoHD which comes with Cineform's "First Light" application. FL works on metadata so I find it very easy for me to make basic color adjustments to video files (say, tweaking my Canon XH footage to match that from my Sony Cams) with very little load on the system. When I get some time in the next week, I might try this kind of conversion and see what I get.

I know that the old manual of RT.X2 suggests to take AVCHD files, and transcode them to the Matrox codec.
So saying that, Matrox should allow the free download from their website....

And they do... that's how I got mine.

Interesting Peter, I'm going to try that...

If the MXO installer doesn't add the codecs and exporters to CS5, the Matrox codec installer will, which is now a free installer. Matrox MPEG2 I-Frame HD is a good 8bit intermediate codec, which I used for a long time before converting to Cineform for 10bit color. That would make a good alternative to AVCHD for MXO2 editing on PC, but is not at all compatible with Avid or OSX.

Did BlackMagic Intensity Pro not provide similar capabilities? While being significantly cheaper?

See point #1.

(Additionally, I didn't have to get the unit with MAX. The normal unit is $450.)

Matrox MXO2 offers output from Avid, while the Blackmagic does not. Since this thread is in the CS5 forum, and those products offer similar features in CS5, that is probably why there is so much confusion about formats and capabilities. Cineform MOV is the only format I am aware of that will play in RT out of the MXO2 from both CS5 and Avid. Avid only supports MOVs and MXFs, and Matrox's CS5 editing modes only support Matrox formats (Mostly AVI based) and Cineform. XDCam MXF files might be another option, but the workflow will be less intiutive than using CIneform.

What version of Avid are you talking about? Because version 5 certainly supports more than that.

Feel free to elaborate. As far as I know, Avid supports converting all imported files to MXF, or linking to them via AMA. AMA supports P2, XD, EX, (all basically MXF) and Quicktime MOVs. (Plus RED technically I guess) It does not support AVI files at all, which is the primary format of most CS5 based workflows on the PC side, leaving you rather limited.

EX is not MXF and Avid won't support it that way. It DOES support it as Mpeg2 wrapped in an Mpeg4 container. And yes, it directly support .R3D. P2 (DVCProHD/AVC-Intra) are MXF, and as you said, MOV. It does not support AVI which certainly does put a crimp in the workflow between CSX/Vegas and Avid. I lived with the pain in Vegas by essentially mostly working with DNxHD36. It was good enough for web work and downconvert to SD. But working on broadcast level stuff was much more painful.