So far (2 weeks) the IST Bluetech mask has performed very well. It seals well without much tension on the straps, has good visibility, and is comfortable. The only negative has been occasional fogging. However, that may be partially a result of the 100 deg. weather here in southern Arizona and the fact that I primarily use the mask for lap swimming on the surface of a pool (hot air+cool water = condensation)......
By the way, the guys at Online Scuba provide great customer service, very competitive pricing, and low cost delivery !