Let me share my experiences with the Meridian.
I bought it in the prospect of using it with the heart rate monitor, but before I could try this function my Meridian got stolen. So I only took it to the water for about 10 times.
I was not really happy with the Meridian for several reasons.
1) It offers the possibility to adjust the depth measurement to salinity and altitude, which I always did. On the CD that comes with it you can find a table with the settings for different diving conditions. But whenever I was diving with others to the same depth our computers would show different depths, sometimes with a deviation of 10%! Sometimes the Meridian showed more and sometimes less. In line diving with measured depth it also was off by 2-3 meters at a depth around 40m. Until the end I could not quite figure out if the table for the settings or the computer itself was the problem.
2) When diving in darkness (at depth in lakes or at night) you could use the "light" function to see the display. The Meridian lights up the digits only (too dim for my taste though), while other watches light up the background. I think I prefer the lighted background. Lighting up the digits only might save battery though
3) Compared to the Suunto D4i the Meridian feels big and heavy. But it probably is more durable.
4) When transferring the dive profiles to the computer I was annoyed by the fact that for some reason I could not view single dives on the graph, it was always showing the whole session. Since you could not zoom into the graph I could not really analyze single dives of a 2h session. They were just some spikes on an otherwise flat graph. This is even more astonishing as it would still show depth and dive times for single dives in the log.
Maybe problems 1 and 4 were software problems unique to my computer, but I will never find out now. I would be interested to hear, if others experienced the same problems. I am not sure yet if I will try the Meridian a second time or will go for the Suunto D4i instead.