I have a 120 gig and an 80 gig drive free. I understand I have to use tivomad to alter a partition on my A drive if my total storage exceeds 140 gigs. If I put in the 80, the only thing I have to do is bless it, and put it in, correct?

Would it be more advisable to do this if I want to avoid tinkering too heavily with my tivo? By all means I'd like to have 160 gigs over 120, but what are the potential downsides of this?