I can not speak specifically to these filters, however it seems wrong in general to take a pure light source (deep blue in this case), use it to fluoresce the surface of the emitter, then take that white light and filter out all but one color range again. For a temporary solution I guess it's not bad, but you're still "throwing out" most of that light you just made.
For a permanent colored light, consider replacing the emitter with an Cree XP-E in the color of your choice. They do not handle as much max current, however given the driver capabilities in the Quark this should not be an issue as the XP-G is not being driven at max current anyway. You will end up with a very bright AND efficient monochromatic light.
The prism itself is a very nifty addition. Wonder if it would fit the Quark MiniX 123 :-D.
