These sound like good reasons for playing Amplitude first, though.
I actually like Amplitude a lot more because the screen layout in Frequency hurts my head. I don't know why but that tunnel stuff confuses me. Probably because I'm old. The flat layout in Amplitude is just a lot easier to look at so I can plan ahead. Plus Amplitude is a lot brighter. Also I like 'Cool Baby' probably a lot more than I should.
Anyway, they both kick ass and are worth full price even now.