i did consider the new Sony device as well but the price is on the high side.
as to my understanding on the firestore and citidisk units, they do have buffer though i don't know the exact length.
from my discussion with the agents from firestore and citidisk, the firestore system is more mature whereas citidisk came out only recently and citidisk made sure that they don't make the same mistakes as firestore but online reviews by users in US have better things to say about firestore than citidisk iirc.
what you mentioned about the added features of the sony unit are also available on firestore such as clip check, clip delete, clip repair, system diagnostics, system reformat and many more built into the unit without requiring a desktop. citidisk's small lcd panel is their biggest problem because you have to remember the symbols to understand what the unit is trying to tell you.
the biggest advantage about firestore is if you buy a DV unit today, your investment is protected as you can upgrade the firmware to make it to a HD unit say two years down the road for a small fee compared to citidisk where you have to decide now DV or HD as they cannot upgrade the firmware....you have to buy a new unit altogether.
i think all external devices require a tight fit otherwise data communications will be disrupted.
and yes tommon, if i do get one of these devices, i will definitely still record to tape as a backup. thanks for your input.