I am considering trying one of the Time ATAC MX pedals. There are quite a few models (MX2, MX4, MX6, MX8, MX12).

I see there are some differences, but all just concern weight (e.g., hollow axles, CF vs composite bodies). They all look identical to me.

Is there any difference in actual performance or function?

Also, is the spring tension adjustable on these (or some of these)?

Thanks.