The 990 offers a 200ms adjustment in 1ms increments. 200ms is a common limit on adjustment, probably in part because if you need more than 0.2 seconds of delay you have some serious video scaling problems of some sort.

There are a number of folks around here with HDMI TV's who have had no problem with using HDMI-to-DVI and DVI-to-HDMI. There are even a few users who had cables that used dual-link DVI connectors and discovered that the 990 will pass HDMI audio through the switch to the TV (although of course the 990 couldn't make any use of the audio signal).