Who makes a GM-70 based SET?

Has anyone compared the sound of GM-70 vs 845 tubes ?
Seemingly they both are used to build tube amps with high power, but both have different origins hence should have a different signature sound. Can someone shed some light here ?

Sibelius, does your amp have negative feedback ? What preamp are you using with this amp ?
Can you give a comparison of this amp with another popular tube amp you might have heard ? That would give a clearer perspective. I have been looking at these guys for sometime but lack of reviews have kept me at bay.

Thanks for the response guys. For some time now I have been contemplating using a good tube amp with my ATC SCM40 but most people discourage me trying mate an 85db 8 ohm speaker like ATC with tubes. I knew about SAC Thailand and their products. I always thought their big GlowMaster based on GM70 which delivers about 70 watts per channel should work in my case. My room is little less than 200 sqft, which should not be difficult to fill. As usual there were no reviews about this amp and I could not gather courage selling my Symphonic Line RG1 MK4 power amp and buy the 70 watter tube power amp.