Hey CC, I tried to find the article from a few years ago, but couldn't. A math professor worked out the formula based on 20+ years of games
...basically it is always (long term) advantageous to play the RL (MINUS-1.5) alt or regular -1.5
when turning a favorite into a dog on the ROAD ONLY.
In all other instances---home games --fav or dog, or road dog into a bigger dog-1.5, it is advantageous to play it straight.
Although you get less of a $$ edge on road -1.5 than home -1.5
The ONLY Long Term advantage is turning those -120 road favs into +135 -1.5 road dogs.
Never is it advantageous to BUY the +1.5.
This is not my principle, and I wish I could find the article. I can imagine I tossed it though because it was easy to grasp, I bought it hook line and sinker, and it has generally proved correct although I never worked it out over 20 years.
Hope that helps for what it's worth.