I'm hoping some of the experts will stop by and advise you but from what I see it sounds like your vet is recommending that you change doses based on the current number? Or a preshot number?
I presume you know by now that we do not shoot based on pre-shot numbers but on the nadirs. Since you're following SLGS the recommendation is that you increase every 14 cycles - which in my estimation is too slow - however since you do not know what dose will be effective and you're following the slower method it's going to take you longer to increase to the numbers he's suggesting. If you want to switch to TR (no dry food, and a curve every 7 days) it would be more aggressive and you'd get him to higher doses with higher impact sooner.
The decision is yours as to which protocol you're following - the worry that I have is that he has a history of ketoacidosis and with these numbers I'd be working on the TR protocol as the danger exists of a repeat episode of DKA. Please re-review the stickie for TR and think about going in that direction.
http://www.felinediabetes.com/FDMB/...-low-go-slow-slgs-tight-regulation-tr.210110/