Some things to consider...
With the enclosures, you don't HAVE to harvest your old cells. You can buy new, higher capacity cells. I have some new Panasonics with 3400 mah, which is 1400 more than the cells in the DVD batts were when new. Those are my first line and then I turn to the older cells for longer runs. Your average deck at your average concert, 6 new cells is more than enough and you wouldn't even need to think about using your backup line unless at a festival. For me, sometimes I will do festivals with video, audio, and streaming from a laptop, so having a large cache of newer and older cells that can power everything is ideal.
The Talentcell has one very big advantage... an on/off switch. I assume this means it can run something even with a very low current without shutting off. The enclosures I use have an auto shut-off when the current drops below a certain threshold. The 6-cell enclosure has a lower threshold... it will run a dr680 (about 200-250mA) without shutting off, but it won't run a small converter box (coaxial > toslink) which draws somewhere around 50mA. The larger 8-cell enclosure will shut off if just running the dr680, but will stay on when running a V3 (around 400-450mA), and also (obviously) if running both a V3 and dr680 simultaneously (around 600mA). Mostly I use the 8-cell enclosure to run my laptop and the 6-cell enclosures to run preamp/recorder/video camera/lights.
A third thing to consider... the 6-cell enclosure has an input and output port and it can be charged at the same time it is used, making it work as a UPS. The 8-cell enclosure has one port for input and output and works sort of the way a lead-acid battery would work, where you can variably charge and discharge from the same connection. This means it can't be used as a UPS and it can't be used as a redundancy (where you have two power sources of the same voltage connected with a parallel cable to a single device).
Oh, also... the 6-cell enclosure has a 5.5mmX2.1mm connector, and the 8-cell has a 5.5mmX2.5mm connector... neither of those are the 4.0mmX1.7mm of the DVD battery output port, so new cables or modding the ones you have would be necessary (I would not recommend using adapters, though they are available).