I would not use Microbacter7, not if already (or after) using Dr. Tim's.
The harder part is establishing the nitrifying microbes that hopefully adapted to our aquariums. All the other microbes are far easier to establish, so to me I don't really see a need for MB7.
Especially since MB7 boasts microbes that work in both freshwater and marine environments. What does that mean? Either these microbes are super versatile and work great in both systems, or they are better adapted to one or the other, or some of them are better adapted to saltwater environments while other to freshwater environments. Either way, yeah you add some live stock and sure, there are probably a lot of host-specific symbionts that live within them, but they would probably also include a bunch of other microorganisms that will fill the roles that the heterotrophs in MB7 may play. Well, I don't know what microbes are actually in MB7, so can't be 100% sure, but hey.