Well ok... consider this. Way way back in the day when the Wisdom was brand new, I started diving with a Sherwood Wisdom, in part to spend down the shop credit for reg repair, and in part because it was not really much larger than an SPG, was very tolerant of deco (used US navy limits once in deco) and deep stops. That made it, at a minimum, a decent depth gauge and bottom timer to back up to custom cut tables for deep air and nitrox diving.
What I found however was that i never used the air time remaining information as 1) it never displayed it as on deep dives deco time remaining was always less and once in deco it gave you deco time, 2) I already new my SAC and was estimating air time remaining already, and 3) in deep diving you do a gas plan and already know if you have enough gas for the bottom time and reserve.
In short - no plusses to using one at all.
There were however a lot of minuses. 1) The battery indicator would say everything was peachy on a 100 degree boat deck then the computer would shut down at 100-150' with 39-35 degree bottom temps. 2) The air integration was prone to failure a) from battery failure, b) transducer failure (I experienced both high and low failures on 2 separate wisdoms) and quick disconnect failures (in this case an Uwatec QD on the HP end of the hose - not the Sherwood QD at the cmputer end of the hose, my last wisdom computer had that - worked great but never trusted it).
So in the end you gain basically nothing, but acquire lots of new and interesting modes of failure that when they occur impact both SPG information and depth/time information.
In comparison a brass and glass SPG is near bullet proof and will work fine even when flooded, and an inexpensive bottom timer and a set of tables or contingency deco schedule will easily back up a wrist computer failure.
