Guppie once bubbled...
I'm looking at SPG's and debating wrist mount or not. I'm thinking wrist mount computer (Versa Pro) and then brass pressure gauge (analog since this is my life) and a compass on other wrist.
Does this make sense or, being a rookie, am I missing something vital?
What you'll find is that there's at least 3-4 logical ways to set things up, and there's plenty of personal opinions (and some chest-beating) about A vs B vs C vs D.
Being able to configure your gear so that you've minimized the number of tasks neccessary to do prior to going in the water is a good thing: if you have fewer things to do, you have fewer opportunities to forget something, or make a mistake. For example, "strap something to left wrist" and "strap something on right wrist" is two distinct actions. Putting both items together into a single assembly (say, in a console) reduces your necessary setup actions from 2 to 1.
Decide accordingly.
Similarly, being able to do a task earlier is better than having to wait until later, because earlier usually means less "deadlines" (fewer errors made due to rushing), and more opportunities to catch a mistake...the last thing you do before jumping in has had the fewest opportunities to be verified. For example, wrist-mounted items cannot generally be done early, because the thermal protection (wetsuit/drysuit) has to be put on first, and your dive conditions may merit waiting to do this until the last minute.
Decide accordingly.
Another thing to consider is your task of monitoring your instrumentation during the dive. If stuff is clustered together, you're more likely to be prompted to look at everything every time, instead of just whichever wrist you're thinking about at the moment.
Decide accordingly.
Another factor that's considered by some is their dive activites. For example, if you're bug hunting, you may be reaching into holes, and a wrist-mounted something can snag. Similarly, some wireless dive computer communication systems are momentarily disrupted by UW camera strobes, as well as require 2 batteries to be maintained instead of just one.
Decide accordingly.
When it comes to issues of streamlining, some things make sense to do, but there's a lot of big claims and no cold, hard data to back them up for us to decide on our own how significant they are. There's also some myopia on the subject, because streamlining isn't an end to its own means: streamlining is merely one way to improve diver efficiency to be able to enjoy a longer duration dive....but its not the only way. It also depends on what type of diving you're doing and where: if you're doing pure drift dives, there is no movement in the water for which a streamlining change will provide any benefit whatsoever.
Decide accordingly.
Finally, stuff can get lost/misplaced/stolen. I've personally seen divers get their same-brand wristmount dive computers confused on their surface interval (diving with the wrong residual nitrogen information is a good way for one of them to get bent), as well as small widgets like this make a leap off of a surface onto the deck of the diveboat, and due to the boat's rocking, try to make a tumbling scramble/dash towards the stern for a solo dive without its owner. Gear loss through broken wrist straps during a dive have not been unknown either, but the manufacturers have gotten much better in this regards.
Decide accordingly.
-hh