I recently ordered both my wife and I identical 2010 13" MBPs. On my MBP I upgraded the HD to a 500GB WD Scorpio Blue, WD5000BEVT ($60 at amazon). Hers has the stock Toshiba 250GB (MK2555GSXF) drive. After the HD upgrade, I did some quick comparisons, and here are my observations thus far: 1) Slower Bootup - Bootup time takes almost 1m30s on mine vs 30s on hers. To even just get to the apple logo on the initial grey screen on mine takes about 30s. 2) Noisier - Mine always makes a quiet whirring sound and slight vibration like it doesn't ever go into a lower power mode. Hers is pretty quiet. 3) Worse Battery Life - My battery life appears to be diminished slightly. Maybe like 10% 4) Slower write speed - I did a quick "time mkfile 10G testfile.10g" and it took 3m30s on mine, and 3m even on hers. 5) Same load cycle rate - For the HD geeks - the SMART load cycle count was averaging about 100/hr on both. I implemented these steps, and now the load cycle rate appears about 0.2/hr. Still worth it for me - To sum it up, I took a performance hit with the upgrade. My guess is that some of this is related to apple firmware vs WD firmware, and some of it just the physics of twice the capacity. However since the hit is not that bad, I'll stick with the upgrade because of the extra space and low cost. Good thing I hardly ever reboot.