Straight Colour Developers at room temp are rubbish, I've played around with it, tried custom recipes to try and boost contrast, and they are generally just rubbish, not even getting to the colour, but simply dMax - dMin can be really small and difficult to work with in any kind of workflow.
30 celsius aint -too- bad mind you for 8 minutes if you really need something with a longer processing time.
The only thing that gives reasonable useable results at room temp for colour negs is:
Split-Bath development - provides much better results than straight colour dev at room temp.
Rehal development - b&w developer at 20 celsius, wash, fix, wash, rehal bleach, C-41 dev at room temp, wash, bleach, wash, fix, wash, etc.
Presoak for C-41 is great, I never do not use a pre-soak with C-41, if you are typically using paterson hand tanks as well, your temperature is stable enough over 3m 15s.