Hi David,
I'm fairly new to Dr. Z amps. I've had my Maz Jr 210 for just over a week now. I'm not a new player though, so I'll throw some ideas out that hopefully will help.
Every amp I've ever owned had 12" speakers. Whether a combo, 212 or 412 cab.
I decided to try the 210 after a good freind and fellow Z owner got one. I like it a lot, and I'm glad I went this route. To my ears, a single 12" driver is more directional (beamed). The 2 10" are VERY efficient speakers and give me as much low end as I'll ever need. They also sound more "dimensional" and open. Also, the 210 and 112 cabinets are the same size, btw.
The only options that Dr. Z offers for these amps are listed on his site. An effects loop, which actually comes standard on the Non Reverb models, and an adjustable direct out.
Currently, the Maz 18 NR models come with the following tubes:
V1 - JJ ECC83S
V2 - JJ ECC83S
V3 - Sovtek 12AX7LPS
5AR4 rectifier
duet of Groove Tube GT-EL84S #6 (which are JJ tubes)
Everyone has their own taste when it comes to tubes. You may or may not want to change tubes. I found that I needed to change the preamp V1 and V2 and rectifier tubes to please my ears.
The speakers in the 210 are Dr. Z's own special blend, made especially for him. Again, I like them very much and don't plan to change. In the other models he uses variations of Celestions, I understand.
You're doing exactly what you should be doing. Asking questions before buying. I didn't have a dealer near me, so I had to do a lot of research!
Btw, I'll also add that I intentionally got one without reverb. I never use it, and I can always add in the effects loop or at the board.
Once you decide to buy, I'd say forget about negotiating price on a new one. Find the model you want and buy it then! Don't wait, or it'll sell and you'll have to wait. These are indeed hand built and last I heard, only about 30 - 35 units go out the door a MONTH!
Good luck,
Ray K.