I play these quite a bit. Some of my outs offer the 4.5 inning line. Some offer the 5 inning line. I look for a few things:
1. Do I like the home or away team. If I prefer the away team, I will shop for prices on the 4.5 inning line. The away team will get to bat at the top of the 5th inning. If I prefer the home team, I will shop for prices on the 5 inning line. Alot of times the juice will be a little ridiculous on both 4.5 and 5 inning lines, which leads me to................
2. 5 Dimes. They offer 5 inning run lines. Favorite lays -1/2. Dog gets +1/2. If I like the Dog, I can win two different ways: There winning after five innings or the score is tied after five innings. If I really like the Home team in a mismatch where they are the favorite, I might take a look at laying the -1/2. But again it really depends on the juice. These have the same good and bad issues to deal with as regular game run lines.
3. Totals: I don't play these as often on the 4.5 or the 5 inning line. But when I do, I'm comparing price to the situation. It really depends on how the home or away team, I feel should be factored in and what the difference in the two lines is. Is it 1/2 a run or a full run. The home pitcher, the away pitcher, tendencies, and trends.
I would suggest having multiple outs for these 4.5 and 5 inning line wagers.