Quest 31 Sillette-Sonic Auto Lock

[gerrybb]

We bought Starquest just over a year ago, she is fitted with a Sillette-Sonic Catamaran Drive Mk2 driven by a Beta 25hp engine. The engine and drive were all new in 2007 by a previous owner. According to Sillette and the invoice the drive was supplied with an Auto-Lock to ensure that when the drive is dropped it will lock so that when going astern it does not lift up and chew up the lifting tackle and probably damage the drive.
It is evident that when the new drive was fitted the auto lock was removed and the 33C operating cable connected to a welded on box on the arm that the operating spring had been connected to, thus reverting to the original operating procedure of having to manually lock the drive down before going astern.
As I have the leg and base removed at the moment to replace the input seal it would be possible to drill the hole for the 33c release cable through the transom and fit the various bits to put the Auto Lock back into operation.
My question is why has someone gone to a great deal of trouble and expense to remove what on the face of it was an improvement that should prevent damage when going astern, has anyone got any experience of the reliability or otherwise of the auto lock, the original manual lock does have the advantage of being positive (Providing I always remember to lock it down). Also the hole through the mounting plate and transom will only be a couple of inches above the 'at rest' waterline and is only sealed with silicone has this caused anyone a problem.
I would be grateful for any advice.
Gerry B