Steve,
Ulitmately it is up to you and you should do what you are most comfortable with. Just to clarify, the surveyor computer you purchased is a very old computer and most likely not manufactured by Mares. I believe it was produced by another company, and branded Mares. This is most likely the reason for lack of information. Also keep in mind, we are here on this board as an extension of our support to the consumer trying to provide more and better information regarding our products. When you look for a new computer, search around and find out which manufacturers are offering this level of support (not all).
For your future information we have been producing our "own" computers for the last 6 years or so. The production, R & D, etc. is all in house, which gives us much greater control over support issues, information, and quality.
I am glad you like the Mares products you have. I hope one day you will find the more recent or future Mares computers to your liking. This summer we will have a new computer called the Icon HD, which will put us at the top of computer technology and design.
Safe and happy diving.
Best regards,