Kitec is yet another type of pex fitting. I know some of the pipes and fittings are OK to mix, like Zurn and Vanguard with some others, but these are a more standard version of the PEX. Wirsbo does not mix with these and Rehau is also different, I don't know about the Kitec. I have seen it, but never worked with it. Kitec pipe does have the aluminum usually, but I don't know about mixing it's fittings with standard PEX. I always try to not mix brands and that is best. PEX is getting very hard to keep up with they need to make a standard for the crimp type and the expansion type and all the manufacturers should have to use it. The expansion PEX and fittings like the Wirsbo is very nice to work with because you can expand the pipe and ring and then put it into a tight place, where as using the crimp tools in a tight place can be difficult at best. You have to be very careful not to put a fitting into a place you can't get the crimper into. I have some compact crimp tools, but they are a pain to use. I hope this doesn't muddy the waters more. If in doubt call the manufacturer of the fitting and the pipe and see what they say, then post and let us know what you find out.