So based on what everyone has said, the HiHy gets better MPG with higher octane.

What's the general opinion on spending the extra $0.10 or $0.20 per gallon (for an average cost of $1.30 to $2.60 additional per tank) for the mid- or good-grade stuff vs using one of those off-the-shelf octane boosters (running $4 - $9 extra per tank)?