Thanks for the reply Angelo.
The MPEG-2 was converted from MTS files using Pavtube MTS converter. There was an Adobe Premiere Pro MPEG present that I used. It works really well on the iMac. I’m not sure if it is intraframe, or quite sure what this is referring to? (I’m still on the newer side of editing, so any informative insights to this is very welcome!)
Is there a solid workflow I could follow to jump from one machine to the other, while continuing to develop rough cuts and organising footage?
Is it worth creating proxies at smaller resolution for the MBR or will this confuse the project files?