TR is a bit nerve-wracking at first (you build up to shooting quite low numbers-- most people with well-regulated cats shoot greens most cycles!), but you do test enough to do it safely. Once you get going with it, it's an excellent method for acheiving good regulation and, in some cats, remission. The mantra for Lantus and TR is "shoot low to stay low"-- Lantus works very differently than the Novalin you've been using. Where Novalin is good at bringing numbers way down, Lantus isn't so much. What it is good at is bringing numbers down gently and then holding them. Once you find the right dose (either using TR of SLGS), it's possible for some cats to basically keep them in normal BG most or all of the time, helping the pancreas to heal. Between the two dosing methods used, TR is a bit more geared to this goal.
That said, I don't think I'd recommend jumping directly into TR if you continue to use the pet meter for testing. It can certainly be done safely that way, but most folks who will be giving advice are much more used to human meter numbers, and while people do make an effort to check what kind of meter you are using, confusion and just habit can lead to a lowered level of vigilance on pet meter numbers. So, just to start, while you're getting a feel for how Bella responds to Lantus, I'd either do the SLGS method if you're going to stick with the pet meter, or TR if you're going to use the human meter. [Note: SLGS strategies were also set using a human meter, not a pet meter so there will be the same difficulty in "translating" the method to pet meters. I just, personally, think that SLGS has a bit more wiggle room than TR, and is thus easier to port over to pet meter numbers]