I would add the Breece Hill drives to your short list:

Q47 - 4 DLT Drives, 60 Slots, about $60K
Q7   - 2 DLT Drives, 28 slots, about $35K
Q210 - Up to 12 drives and 210 slots, 1-6 drives, 210 carts 7-9 drives, 140
carts, 10-12 drives 70 slots, about $130K for the 6 drive, 210 cart config.
(Not supported by ADSM yet, but soon)

I haven't seen problems with DLT7000 since the first flurry of problems.
 One wants to make sure and relabel already used tapes before using them in
7000 drives.  If this isn't done, the old label, which may have been
written at a lower density, will indicate to the 7000 drive to write at a
lower density.  Not the desired behavior.

Kelly