storage - less is better, embracing constraints

Lucy and I have been discussing photography backups and we'd been thinking about buying an external drive, maybe 250 or 400G. Somewhere to stuff the clutter. Then Joyent launched Bingo!. We already use strongspace to run an automated mirror of our Documents folder, so I know they are good.
However it is a maximum of 100G, much less than the 250 of even 400 we had been planning. So, I thought a while and realised that this is actually an advantage, if we see it as a constraint. We don't have 100G of pictures yet, so we don't need all that space, it will make us delete the rubbish pictures and keep the best ones. By the time we hit 100G, Joyent will be offering 250G I'm sure, but the constraint will have helped me to winnow out the chaff. My only decision is to how tight to make the constraint, 25, 50 or 100.