First and foremost, from your description what you're facing has nothing to do with AVCHD bug in CS6 (see this help section on the bug symptoms). Moreover, Sony PMH, unlike e.g. Sony Content Browser, performs stitching spanned MTS clips into a single M2TS file on transferring to a computer by default. Hence, there is no chance to face spanned AVCHD clips bug while using a single rewrapped M2TS file by definition. You can download a sample of spanned AVCHD clips, which exhibit the bug, here.
Second, 8 GB of RAM you currently have installed will hardly allow you to work with such a resource hungry codec as H.264 efficiently.
Third, post at least a screen shot of what you consider to be the issue - without seeing anything it's hard to guess what is going on at your side...
Indeed, I have minimum recommended specs. Rendering / encoding in Premiere and AE CS6/CC is pretty slow. Nevertheless, I've been otherwise working fine and regularly publishing H.264 for about a year. Sometimes, you have to make do. That information was more to provide operating system specs, in the event this is a bug issue.
I'm not at liberty to post the footage, or I'd have posted video samples. I have lighting issues that show up similarly in stills. The issue is only apparent during playback both inside Premiere and after encoding with Premiere. (New project, new matched sequence.. otherwise unadjusted.) I probably should have noted that, though I don't think that's the issue. I've had similar lighting issues with other formats that still imported and played back fine.
In the meantime, I found a workaround I will post for those looking. I converted the original file to an mp4 using Handbrake's default settings. The mp4 works a treat in Premiere. Job done. I'm either incorrectly importing this particular format and/or Premiere is having issues interpreting it. Once I'm past this deadline, I'll compare Handbrake's default settings to my Premiere project settings and see what I can figure out.