I like how the Types are just their regular freighter line, while the others have their own special designations. If anything, I'd say that the T10 should be renamed to something else, as it is basically a keelbacked T9, which would then open up the name T10 for something more in line with the Cutter.
The missing numbers I see as being a good way of future proofing the line, as they provide little slots for FD to backfill as necessary. For example, we could eventually see a "Type-8 Compact", that is a T7 with slightly shorter landing gear so we have a medium trader to compete with the Python. Likewise, it would be nice to see a "Type-5 Commercial" that is a slightly smaller T6 that can fit on landing pads.