As Tom pointed out, tempered requires a measurement prior to tempering -- and then you CAN'T make any adjustments. Laminated safety glass can be cut (somewhat) and replaced more easily.

The process of making tempered glass involves heating and then cooling very rapidly. Usually that is accomplished by a "mist" or "spray". In my experience, the glass only comes out to the site once: After it's fabricated. The measurements are made, then it's made.

As for strength -- well bullet proof glass is almost always laminated safety glass (or, if plastic, Lexan). That's for two reasons. If tempered glass fails, it turns into "popcorn" and shortly will be laying on the floor (i.e. deck, etc.). It's essentially gone and you have a whole bunch of little pieces of glass which, while not shards like plate glass, would be a mess to walk on, etc.

Laminated safefty glass is made either with regular glass, or layers of heat strengthened (not quite tempered) glass that are sandwiched between two layers. It's like an auto windshield that stays in place even though broken.

Tempered glass is more vulnerable to a sharp object causing it to shatter. A stone that would cause a cavity crack in a windshield will make a tempered glass sheet shatter. Tom's (so far) happy experience with his ports on the sides of his cabintop are probably in part from the position of them and their relative size. I'd be more concerned with the dodger where people and things have a way of meeting it.

If you had a shackle get loose, or a winch handle drop, or something else like that -- then your tempered glass enclosure would be at more risk in my opinion.

If you plan on using a wood or metal (stainless or aluminum) mullion system, then make sure you allow enough expansion and contraction capacity -- along with dealing with the flexure issues of the boat moving through and dropping from waves.

The use of Lexan would bring to bearseveral issues: i) it is subject to UV degradation over time (which canvas covers could help); i) it's coefficient of thermal expansion is greater than glass (so you need more expansion and contraction capacity in the framing); and, iii) it is subject to scratching if you don't treat it like plastic when cleaning it.

I think that you "framing" plan, opening window, and general construction of the dodger would probably lend itself to Lexan. I wouldn't used tempered there, but I might use laminated safety glass -- though I doubt you'd like the cost.