The addition of GPU mining to bitcoin actually enhanced security of the coin.  I saw this discussed on BTCe with Artforz and it was generally held that the more expensive the mining hardware required, the more reinforced the bitcoin chain becomes.

What I think would really add a lot to LTC is to implement a chain that halves in six months but does so incrementally, that is, every block or 200 blocks or whatever decreases a certain percent, with 50% block size at six months.  Liquidcoin has proved this to be easily possible.