Having used Logic 5 and Cubase SX on a PC, I can tell you that, after learning to use it, Logic proved to be the more creative and adaptable system. This puts me is an awkward situation, but that's my problem!

Forget how 'nice' the interface looks, think about what you need. Logic is geared slightly more towards a hardware setup, and SX slightly is more soft synth/plugin friendly. This might be different on the mac... And will change over time.

Logic comes with EXS24, which will do you in place of Kontakt. It also has much more professional sounding effects included in the package, the EQs are better, and the included synths are very sweet-sounding. The synths in Cubase are OK, but I personally prefer the Logic ones. (I'm talking about the Platinum edition here). Even the simple ones just scream quality.

You WILL have a steep learning curve learning Logic, if that's the way you go. However, I'm here if you need some starting points. And once you get the hang of it, it's gorgeous...

Another thing to think about is the fact that Apple should now be working very closely with Emagic, in order to optimise Logic for their platform. This means that you're buying into a line which should improve for your machine faster than all the competition. Thus any memory/processor issues will be ironed out pretty quickly.

Ask yourself, also, why you're being offered a 'sweetener' to buy Cubase...?

If I had a Mac, there'd be no question which sequencer I'd invest in.

T*