Some get software issues (especially SSDs), different connectors, height issues, etc..
There's very few issues that are software related (and most come from people trying mistakenly to enable TRIM when other means can deal the problems more effectively). There is only one connector really right now (SATA) unless you're dealing with a MacBook Air, and the height of the drive is not a factor with any of the Unibody computers, plus most drives are 9.5mm or smaller now, so few have issues even with the older computers. Basically, you can pick up any drive you'll find on the shelf and use it with any MacBook Pro without significant worries, outside a few SSD's that do seem to have specific issues.Some get software issues (especially SSDs), different connectors, height issues, etc..
Some of us need the extra storage...that 750 gb might be necessary. The second generation 750 drives have 8gb SLC. The reviews have been very positive; in real world stuff after it learns what you're using it compares pretty favorably with a MBA. And certainly a good value.FWIW, I had an early Momentus XT 500 gig with 4 gig cache in a windows laptop and experienced no percieved improvement in performance over a generic 7200 rpm spindle.
I will suggest that if you are going through the effort of swapping he drive, swap in an SSD. Night and day difference, performance wise.