Installed 256GB Crucial M4 into early 2008 MacBook Pro 15". Boot time about 20 sec. I have a bunch of startup items and they launch like lightning as do apps. It's beyond worth it. I am capped at 6GB RAM, needed more until now. With SSD, I can quit apps & relaunch so fast that RAM is no longer a constraint. Also, I needed Snow Leopard for one old app, so I have a second partition for that, can boot back and forth in under a minute. And it's almost as quiet as an iPad now.
On the upgrade cycle, similar to others, iPhone every 2, Mac every 3 while passing the old Mac to a family member, iPad 2 still feels great, so hard to know when that will be replaced. Despite being an early adopter, first Mac in '84 and first iPhone early days, we waited for iPad 2. In holding pattern now waiting for iMac 2012.
Interesting.....the average windows computer boot time is around 13 seconds I would say, most of whom I've seen are getting 10 seconds with a sandisk extreme 120GB SSD, which is the one I'm putting in my build I'm doing. But I guess other compenents do play a part in that but mine should easily get 10 seconds if not better. Thanks for the statistics much appreciated