As I understand it, there is a limit to the number of customisations you can have for each parse file? Could someone expand on this? Is it a set limit or a recommendation based on memory limitations etc?
If you do need further customisations, is the only work around to duplicate the parse file and all of its related images, css files?
The limit is based on time and memory (mostly memory).
We are currently working on a HIPO job to parse designs and customisations which will get around these limitations.
The limit is based on memory/process time limitations within PHP. As we process the main parsefile and all attached customisations at once, if there are too many assets to deal with, PHP either runs out of time (as defined in the max execution time limit in php.ini) or runs out of memory.
We find that most installations can support 5 or 6 customisations per design before this becomes an issue. We are working to resolve this in a future version, though.
Damn, Greg beat me to it! 
Cheers Guys, you're quick off the mark for a monday morning!
So it isn't an issue at run time? only when we first process the parse file?
If all the customisation does is refer to say a 2k css file and a 2k image and we pump up the time out in php.ini could we run this as a job overnight or something?
You guys know our set up here so would memory be an issue?
Or is a run time thing after all?
No, not a run-time issue.
The job probably wont take that long to run (depending on the number of customisations). However, you could leave it run overnight if it does take that long to run.
Thanks Greg, I shall look into it some more.