Huh? A Hammond for Bach? A "Mighty Wurtilizer" (sic) for Bach?
No, no, no, a thousand times now. Would you try to play Purcell's
(Jeremiah Clarke's) Trumpet Voluntary on a Vuvuzela or a Kazoo?
First of all, if you're going to play Bach, E. Power Biggs style, you
might consider the actual instrument that Biggs chose to have built
for the purpose. That is the Flentrop organ in the Busch-Reisinger
museum at Harvard.
Take a listen to Biggs playing Bach on the instrument:
https://www.youtube.com/watch?v=m4pb_W_dSK8
These are sounds that you are not going to get out of a Hammond or a
Wurlitzer, for the very simple reason that they weren't designed to
do it.
Here is a link to a description of the instrument, how it came to be,
and a stoplist.
http://www.hcs.harvard.edu/organ/organs.php
I'll point out that it's a relatively small (27 ranks) instrument,
with enough tonal resources to play other than Bach-era music. What
it won't play are some of the 19th century French whoppers (Vidor,
Franck) and later that required the (very different) tonal resources
of Cavaille-Coll's instruments. Those require a solid reed pipes
chorus (jeu des anches).
There are electronic instruments far more suitable for learning your
way around Bach, Pachelbel, Buxtehude, and the like. One that
immediately comes to mind is Rodgers. Another is Allen.
Now, by way of background: I was one of the "pick-up team" that Dirk
Flentrop hired to erect the Busch-Reisinger organ in 1958. Listening
to Flentrop, Biggs, Charlie Fisk (C.B. Fisk in Gloucester) Walter
Holtkamp, and a bunch of others involved in the "Organ Renaissance" of
the mid-20th century talk about organs was, shall we say, "educational."
Later on, I did move to Oregon and worked for Tektronix, so had an
opportunity to discuss what Rodgers Jenkins was trying to do with his
instruments. When it comes to quality, Jenkins was ex-Tektronix, and
probably a lot better prepared than others to build something really
solid. I'm not so sure about Allen.
I think if you want a good practise organ for the really classical
organ literature you need a suitable instrument. Here's a used
Rodgers that looks a lot more suitable:
http://www.ebay.com/itm/REDUCED-Rodgers-530-2-Manual-Digital-Organ-w-MIDI-11-yrs-old-Internal-spkrs-/181379788474
Take a look at the stop list.
Hank