"I have had over 20 3D SLA/LCD printers. The new monochrome ones are amazing. I compared the E6 to the Mars 2 Mono, and there are a few reasons why the E6 is better in my opinion:
1 - It is significantly faster - the exposures are around 22% faster. I have measured them both and the E6 has more light output.
2 - It has a network interface on it. This allows me to run a print farm and start and monitor prints from another room. I no longer need to pull USB sticks, load files, and run back to the printer to load the file.
3 - It is quiet - the Mars fan runs when the printer is not printing. The E6 is silent when not printing.
4 - Replaceable LCD. It is unclear if Mars will sell you an LCD. You may have to buy a new printer, or ship yours to have someone else replace it. Epax said they will sell LCDs.
5 - The build plate on the E6 is secured with four bolts - and is less likely to go out of tram when removing tough prints. In fact mine has never gone out of alignment. My Mars has because it has a ball pivot mechanism.
Aside from all that, this was the first printer I have unboxed and started a print within 3-4 minutes. I have never had a failed print after several hundred parts.
Also, the E10 is great - have not had a single failed print on that either."