I have a 15 in 2011 2.3 GHz mbp with 8mb and I use photoshop daily. It handles everything very smoothly and no lag. I can have multiple windows of photoshop and illustrator up and running and don't have any delays. I also have the anti glare display, because with glossy you cannot use the computer if any sort of light source is around. Even if the mbp is slightly less powerful, the availability to take your work with you greatly outweighs that nominal performance boost.
I went with the MBP, and also got a keyboard, magic mouse and magic trackpad. Why did I get a magic trackpad? Well when I'm at home using it as a desktop machine, I'll have my macbook in the corner of the desk. I'd have to lean over to get those touch gestures from the Macbook so I got a trackpad to have right next to me, with much bigger landscape.
I think you guys tend to forget (but I'm not sure if I mentioned), I'm in Australia. The prices there are not the prices here. They are jacked up a fair bit more.
I went all out and got the best MBP with Antiglare + the accessories. This was close to 3.5 grand.
If I was to get both iMac and MBP, they would have been the lower end models which I prefer not to do. If I had of chosen the MBP and cinema display, again, a lower end MBP. Plus, I don't really like the ACD because of the glossy option. It's a great display, but for it's price, there are cheaper options that will do great too.
Many of which I'm still looking at, but I think I've decided to just go with two 24" monitors. One for my PC (Since it's monitor is dying), and one for the MBP alongside the MBP's screen. 3 displays in total on my desk including the MBP's.
I justified my decision by thinking how much I'd love to take my computer around with me and how useful it would be. Turned out, I really love that option of being able to have my mac where I go.
The MBP will be used for video, photography, music, and web design. I got the premium model to make sure I can go heavy without any issues. I am a pretty full on user in the respect that I like to have a LOT going on at one time on my screen, but I'm productive that way.
As for gaming, I decided my PC can be fixed up relatively cheap and still play the latest and greatest. I recently upgraded it's GFX card so I don't wanna put it to waste.
In summary, my decision went like this.
MBP - Productivity & Portability.
Existing PC - Gaming, and whatever else. I can upgrade it to have more power than an iMac anyway, which I will probably do as I like the best of both worlds.
All the PC needs is a CPU and RAM upgrade and it will kick ass.
And who knows, if I'm overly impressed with my MBP, I will see that iMac in the future, but I think my decision and what I have now will do me just fine.
Thanks everyone for the input, really helpful!
P.S, can anyone suggest either 24" or 27" monitors excluding ACD?