They're nice lights and well built.
I believe the clear glass is much cooler in K.
Main problem is over time and use all flash tubes colour-shift by losing their vacuum so ensure you meter each head's colour temperature, and then simply compensate with the right gels. If you don't have a colour meter you might work around this by shooting a pure white tile (in darkness to isolate the source) with each light, then white balance it onscreen to gauge the approximate the shift of each head, and then compensate accordingly with gels. It's less accurate but will be much better balanced.
