Twilight, he's definitely a marble betta. A good way to tell is to look at the gill plate- marbles often have oddly colored gill plates. That's why people have to be very careful when buying "Koi" bettas. They are just marbles, and nine times out of ten they WILL shift colors during shipping. Here's some Koi with the colored gill plate that tell you they're marbles-
bettas are classified as an iridescent color over a flat color. Most commonly iridescent blue over opaque, like this guy-
Here are the faults a grizzle could have-
Too much black- would be moved to marble category.
Too much red- would be moved to multicolor category.
A butterfly pattern- would be moved to the BF category.
Too much opaque/pastel, not enough iridescence- could be moved to the opaque/pastel category.
You don't see too many of them, but they are gorgeous. Kind of a pain to breed for, though.
As for the acclimation, I always cut the bags open and dump the fish with the water into a jar. I float the jars in one of my big sorority tanks so that the temperature acclimates, and every twenty minutes or so I add a turkey baster full of their new tank water. After about an hour of bastering (if that's a word… rofl) I dump them into ther new tanks. It's always worked for me, and I've never had an import just die on me like some people have. o_O