I have 3 all 14-15mths apart. So Ds1 was 2.5 when Ds3 was born (nearly to the day).

To be brutally honest, it was perfect in the beginning, I definately found it easy to deal with 3 kids under 2.5; its now that they are all preschoolers that its insanity and then some. The only thing keeping me going right now is that Ds1 goes to school next year. They are close, definately, but for the most part they fight and tanty and its terrible 2's x 3. I sometimes wonder if its because they are all boys, if putting a girl in the mix instead of a boy would have changed the dynamic.

So I definately would not encourage it unless you are 100% certain you can survive hell on earth.

Also, having two or more close together like that stuffs the dynamic if you choose a larger gap for subsequent kids. At this point in time baby #4 will be nearly 4yrs younger than Ds3. I worry alot about the baby feeling left out or isolated from their big brothers because the boys are close and are at pretty much the same stages for most of the time. Moreso if baby #4 was to be a boy. Its making us consider having 5 children to allow for a close sibling gap again.