I would not go directly for "num TRs above mot limit",
but rather "censor fraction", as well as "fraction TRs
censored", which is per stimulus class. In particular,
apply a fractional limit per stimulus class that you
care about (ignoring those you don't, such as error
trials, say).

Let me go the other direction and mention fields that
seem reasonable to use for subject removal:

average censored motion : average motion after censoring
max censored displacement : max pairwise displacement (post censor)
degrees of freedom left : maybe more clear than "censor fraction"
fraction TRs censored : per-stim class fractions

- rick