When I take Dog +1.5 It's always 2:0 3:0
When I take Under 3.5 it's 2:2 3:2 3:3 4:3 1:3 2:4
Look at Crvena Zvezda, 3:2 against a +3500 dog. If I had taken Dog +1.5 it would've been 3:0 as usual.
Overall I still prefer U3.5 because it's like Dog +3.5 if they don't score. But when my numbers show equal value on both bets I never know if I should take both or only the under.