Don't know about generally, but for this particular vote, in Scotland, the youngsters are, in the main, fully engaged and very savvy about the pros and cons.
It is also right that they should be enfranchised, as they will be affected more that the rest of us.
My own personal observation, unsupported by any real evidence, is that young voters are generally in the No camp.
There is a small percentage of skew in young persons' (not necessarily under 16) vote.
Scots students studying outside Scotland have mostly retained their Scottish addresses so that they get to vote. On the other hand, non-Scots students studying in Scotland (and many of our migrant workers as it happens) have registered their Scottish addresses so that they too get to vote.