Strobes have production tolerances, just like everything else manufactured. The color temperature of your lights depends on a great many factors, and the marketing department will almost always quote you numbers based upon an ideal environment. This is true of small speed lights as well.
With very few (expensive) exceptions, all strobes vary in color temperature as you adjust the output. Due to the nature of the physics and manufacturing involved, color temperature is warmer at full output and colder at low output. Some equipment varies by more than 600 degrees Kelvin as you adjust output, some by as little as 50 degrees. Where you will most often notice color shift is when your strobes are set to widely different power levels, say one at full power and one at minimum power. Output settings that differ by less than 2 stops are not often noticeable in most photographs.
As to the question of whether you will notice color balance issues using a mix of small flashes and a 600 W/S strobe, the answer depends on your sensitivity to color, the color accuracy of the lights, the power levels of each, the age of the flash tubes, etc. I'd suggest shooting for a while and see if you notice a problem. If you do, then take measures to solve it. If you can't see any color issues then don't worry about it.
If you **do** notice color problems, the easiest way to go about solving them is to use color correction gels in front of your lights. If you want to get picky about it, you can go spend $1000 on a flash meter that measures color temperature and then gel each light until everything matches exactly. But unless you are shooting for clients who are really picky about color you can usually get by using a gel that converts light from one color temperature to another.
People who do stupid things with dangerous substances often die! -me