Is it easier to exercise with the iPod nano 6th or 7th generation?

Does anybody have any opinions or experience on running/exercising/lifting with the iPod nano 6th generation (either as a clip or a watch) and/or the 7th generation?

Pros for 6th generation: Is versatile in that it can both be clipped or strapped as a watch (don't need to use an armband). Is lighter in weight.

Con for 6th generation: Older model. Might be harder to control music (but it should be fine with power button being able to pause/play).

Pros for 7th generation: Newer model. Easier to control music.

Con for 7th generation: Might not stay in pocket or on clothes so well with a clip because iPod is larger.

Help!