I love my Macbook Pro but... you can't put 16GB RAM in the current models. Max RAM is 8GB. Also I have a 17" model and rumor is that nobody's buying 17" any more and they'll discontinue soon.
There are rumors Apple is going to do something more like the Macbook Air for the replacement to the Macbook Pro line. Lack of an optical drive is no big deal, and I'm sure Apple realizes there are pros who need a powerful machine.
I think an SSD drive makes a difference in terms of quickness, but it's too expensive (in my opinion) to use for regular storage. I have an SSD in my Mac Pro for the OS and user/system folders, and store all my documents on a regular ATA drive. This is a pre-Thunderbolt model or I'd consider getting external Thunderbolt storage. Firewire and even USB2 are pretty quick though. I also have two network drives for backups and bulk storage, and while you wouldn't want to try to record multitrack digital audio over ethernet (short of gigabit), you could certainly do so over Thunderbolt, Firewire, or USB2 or 3.
Used Macbooks hold their value well, which is good for the seller but means that for the buyer, they're not really a great option. You can usually get better, newer tech for not much more than last year's tech. If you want a 17" screen you may want to buy a current model rather than wait for an update. Of course, I could probably do just as well with a 15" considering I'm usually connected to an external monitor anyway. Given the pixel density of the 17" screen, I actually have more screen real estate (more pixels, if not more square inches of screen) on the laptop screen than on the external 23" monitor next to it.
