Just my $.02, (which, unfortunately, due to the state of our economy, isn't worth stooping over to pick-up!). I have had the RH Designs StopClock Pro and accompanying ZoneMaster II in use for about 2 months. (Which was purchased quite pleasantly from a fellow APUG'er. Thank you, Jim!) I have been using the clock for about 60 days now. Bottomline, I am hooked. Tremendous savings in materials,time, repeatable accuracy of prints, split-grade, dodge, burn, scaling size up/down, time for my nails to dry....oops wrong forum!
The learning curve on the timer is not steep. I am still trying to get an apprentice level competency with the ZoneMaster.
I have no practical familiarity with the MetroLux, but will wholeheartedly champion the StopClock!! As an aside, RHDesigns supports APUG and Les is a key contributor to both!
Hard to go wrong!!