Yes, the G-15 was definitely a digital computer, but I'm not aware that it had any
"add-on analog element," at least not any that was a standard Bendix product.
There was a differential analyzer, the DA-1, that attached to the G-15 and used some of
its drum memory lines for storage, but it was a digital differential analyzer, not an
analog one.
There was a connector on the back of the G-15 cabinet to which a user could attach data
collection equipment, but this, too, was digital -- the external signals were made
available in a one-word "Input Register" the G-15 could enable, disable, and
read, but any A-to-D had to be done by the external interface to the system.
As to the G-15 being a personal computer, I think it was pretty much in the same league as
the LGP-30 in that respect. They had similar electrical and floor-space requirements, and
their costs were not all the different, either. It was definitely a single-user system,
and my impression is that the G-15 was typically operated by the people programming it.
Its design was not conducive to closed-shop operations.
There was at least one person who used a G-15 as their personal computer -- Harry Huskey,
the designer. Apparently the deal he made with Bendix to do the design included him
receiving a G-15 for his personal use.