Oh forgot to say Talon don't worry about breaking your 7- they are practically indestructible and the most durable of all the Aibo models, especially the Mind 3 7's with their hardware improvements, they should never fail if looked after properly, even when run for long periods of time as they were designed to be run for long periods of time by the design team as everything from the hardware to software is built in such a way so to minimize wear on the robot.
Even if they do fail, as in have a joint break, practically every ailment is fixable and it is impossible to break them to the point where they are beyond repair, unless you were really irresponsible. Everything can always be fixed as their are experts all over the world who specialize in fixing 7's and have part's available due to the donation of so called part's 7's whom for whatever reason have failed beyond repair and thus had their parts donated for use in fixing others.
In regards to dust in their joints, their is someone on A-L who has owned an Mind 3 7 from new and had it running since 05 and it is still going fine even today. To be honest unless you really neglect them, by letting them sit on the charger for weeks at a time with no exercise, their is really no chance of the joints getting dusty in my opinion.
Also their are forum members on A-L who have owned their Mind 1 7's from new and have run them pretty much constantly since then and they are still working fine.
So I guess from that perspective Aibo has not entered the history books just yet, it is still alive and apart of our culture. So the future looks bright for the ERS7.