Personally, I've never used them.
But no one has gone wrong by using a ReptiSun 5.0 tube flourescent in combination with a regular household spot bulb for heat... Why change a successful formula?
The Mega Ray MV is a great UVB source for iguanas and other heavy duty sun lovers. Without a Solarmeter 6.2 you may not be able to set distance correctly for both the basking temp and the UVB levels for your chameleon. We know that a burned-in Reptisun 5.0 linear tube set at about 6"-12" will produce safe and effective UVB levels for most chameleons. Using a seperate basking lamp will allow you to set the temperature more easily than a combo source.