When I mentioned the option of adding a signature to the back of the print it was because Vaughn mentioned matboard and I incorrectly assumed he was refereeing to the overmat which may be very easy for the client or a custom framer to discard. If you are drymounting the image and signing the mounting board (which may or may not be mat board) then signing the back is less of an issue since the mounting board is now a permanent part of the artwork, unless your overmat will hide the signature.
In regards to t-hinge vs drymount it is similar to the question of zoom lens or prime lens. The answer is personal because it depends on what you are doing, who you are doing it for, what you are doing it to, and your financial and equipment resources. For instance, many people will t-hinge not because they think it better than dry mounting but simply because they do not have the justification for the purchase of a drymount press. Another reason to t-hinge is that drymounting will destroy certain types of artwork (not much of an issue for darkroom prints but some inkjet prints canít take the heat). Drymounting is a great tool for photography since it gets rid of the issues of paper curl and makes it very easy to float mount allowing 100% of the image to be displayed.
As far as which provides more image permanence the most critical aspect are the components you are using. If you drymount to a regular foamboard it will not be nearly as archival as a t-hinge to a Bainbridge Artcare rag mat board. The most ideal components have the following characteristics:
100% virgin alpha cellulose or cotton rag - no recycled materials
lignin, rosin and alum free
fade and bleed resistant
neutral pH (for non buffered boards)
buffered with a buffering agent (CACO3 - calcium carbonate) to help maintain an alkaline reserve (if not using an acidic printing process)
These items will ensure the components used in the process are not harmful. Another option is the Artcare process Michael mentioned which Bainbridge holds an exclusive license on. Artcare is a Zeolyte technology that adds molecular traps to the mounting and mat board which provides a layer of active protection since they will absorb and neutralize harmful chemicals making their way into the framing package.