Well first off let me say that I have had no problems at all with my MicroDrive and my job's microdrive. I think what you need to figure out is how often you plan on shooting and for how long. I can easily zip through 107 shots (1gb microdrive shooting RAW) in about half a day. What I have decided on doing is getting a digital wallet so that I can store up to roughly 5gb of data. That gives the ability to take roughluy 600 shots (500 on the wallet and 100 on the mcirdrive). A 512 might be just fine for you, or myabe a 512 with a digital wallet?