Hi Matt.
Great idea to launch a thread on this.
After falling out of favour with many keepers because of reliability issues etc. some time ago, the MegaRay has been making a come-back. The 100 and 160 watt Mega Ray Solar Raptor lamps made in Germany for the European market have been a success and are considered reliable.
Although Matt has asked about the Mega Ray and Arcadia lamps, it's worth saying in the passing that there are other combined lamps such as the powersun and solarglow. Both of those have low uvb output relative to the Mega Ray and Arcadia and in my opinion not worth buying. (see here for a You Tube review
https://www.youtube.com/watch?v=s35Z8X55tv4)
I know from other forums that the European MegaRay Raptor combined mvb lamps have a good reputation again but there are issues with the 100 watt USA Mega Ray lamps.
Personally I switched to using T5 Arcadia tubes for uva and uvb with halogens for heat. I reckon the Arcadia tubes are great and they even have a more powerful one than the T5 now, the Dragon, producing a whopping 14% uvb. Also the tubes never blow up and the halogens just go out eventually. But some prefer a combi lamp.
Whist I'm rambling (if anyone's reading!) we were promised a revolutionary new lamp in the form of metal halide. For various reasons the Mega Ray Metal Halides haven't taken off in the way that they might have done. Possibly because you have to buy a ballast at £90 as well as the lamp and it doesn't produce any heat so it's not a combi. So again it means a halogen or something as well and my thinking is why not just use a T5 tube then?
But, in some countries the metal halide (also known as HID) lamps are thought of as being the best.
And to further complicate matters, Powersun and Luck Reptile have brought out metal halides that say they do heat as well as uva and uvb and the ballast is part of the deal. I haven't tried either of those and I haven't seen any reviews that I would trust either. Given how the powersun uvb lamp is, I personally would hesitate to buy their HID.
So if other manufacturers are going the HID metal halide route why are Arcadia not doing so? Well, they are. For fish and fish only. It looks like their 'marine' lamp isn't producing heat. For reptiles Arcadia are sticking with their tubes (no heat produced) and old-school mercury vapour D3 lamps. It's just my opinion but I like Arcadia because they provide loads of good information online about reptile lighting and don't try to pretend it's all very simple, since it's not.
So for your combi lamps I reckon it's between the Arcadia and MegaRay and the 160 watt of either packs a punch in uvb and seem to last quite well.
What I've found with the T5 tubes is they last a very long time but I only know that because I've got a solarmeter. As I'm using them with quite cheap halogens I reckon this is the right route for me at the moment.
But if there is a really good metal halide that produces heaps of light across the right parts of the spectrum and heat as well and doesn't cost too much then I'm ready to be persuaded.