I have been designing and running H2H versions of the ottoneu game on both Yahoo and ESPN for going on seven years and have used multiple rules/settings in trial-and-error to find combinations that had a balanced and agreeable game-play.
With more than 2 active SP slots and an IP limit, the incentive to carry an excessive number of SP’s and exceed the weekly limit is too great. It ultimately robs the FA pool of SP depth while Hitters who should be rostered get swapped out in favor of the extra arms; teams will even go with one or two empty Hitting spots on the active roster because the edge in those additional ~5pts/IP x 10-20 IP’s over the limit is greater than the ~5pts/G x 4-6 Games you’d be getting out of the Hitter. Inevitably, owners who are slow to the game or didn’t see this advantage before the draft will feel shorted, and the season will be lost for at least half of the league.
As @dfinan points out, there are other ways to compensate for this with other services- however, Ottoneu is different. For example, the payroll cap functions in lieu of a transaction limit- which actually adds some strategy to the game as you could potentially stream SP’s in an important matchup to try to get the most starts out of your week if you have the budget space to do so and don’t mind being out any player you cut for (at least) 30 days. The one thing that can’t be done, as Niv describes in the links he posted, is a hard limit on the number of IP or GS- and that’s true of every fantasy service.
This is why the natural limit of 2 SP’s is appropriate; more than that and the format will skew heavily toward pitching, regardless of an IP limit. There will be times when more than 2 of your SP’s start on the same day, but as it plays out over the season- because of off-days, rotation differences, weather-postponements, etc.- those three guys that start on Opening Day aren’t going to line-up on the same day every week. With all the variables that go into each matchup, a 2 SP limit does not impact the league half as dramatically as a few teams controlling the SP market and exceeding the IP limit every week does.
So you’ll have to make tough decisions on who to start each day just like any other baseball manager with an excess of talent at one position does- and everyone else in the league is on the same level playing field in doing the same thing. A balanced game centered around strategy is the Ottoneu way; welcome to a better brand of fantasy baseball!