I run Macromedia apps on Mac all day every day for my living and I have no complaints. I get those great apps AND the productivity of the OS X environment.
I really like Macromedia apps... and I find using Director, Flash, and/or Dreamweaver with OS X Exposé is a very nice experience. All those windows suddenly become manageable.
People like to pick on Macromedia but I disagree. I think the two main complaints that I DO find to be legitimate--but things of the past--are:
* Making you buy Director for Mac AND Windows if you want to make apps for both platforms. BUT THAT'S NO LONGER TRUE. I make Windows software on my Mac with Director MX, and I no longer need Virtual PC and a second copy of Director
* Framerates for Flash playback on Mac. But Macromedia announced last year that they were working on that, and expected faster rates with each updated player version. And I have no complaints about the current speed myself.
I agree that Macomedia sometimes uses quirky UI stuff--but I think Adobe does too. And in both cases, once you're used to it you can be very productive. Macromedia apps are highly capable--nothing can touch Flash, Director and Dreamweaver for my needs.
And Macromedia supports Mac-specific features, too--windowing stuff in Director, for instance, that's Mac-only but you can still use it in your creations.
So I'll be using Macromedia on Mac for a long time to come--owned by Adobe or not. If people notice any sluggishness that I'm not noticing myself, I wouldn't worry about it much on a new Mac. Maybe on older Macs.