Amerok makes no sense when he mentions time signatures such as 11/9, 4/9, 7/9, or even 22/9, because such time signatures do not exist in music. Let's break down what this means. Metric, meaning the time signatue in which the music is in, and modulation is the implied transition from one time signature to the other (in this case, results in a smooth transition). In metric modulation, there is a mathematical pivot in modulating from one meter the the other. In most cases, this can be known as a subdivision of the original tempo (in some cases a polyrhythm of the original tempo).
Metric modulation example of a time signature of 4/8 in a tempo of 120 bpm:
An implied modulation of a FASTER feel would be of the tempo of 150 bpm (1/3 faster than the original tempo) using the same meter of 4/8. The number of times you play each original pattern would also increase by 1/3. Metric modulation is a change of note value...from the first is made equivalent to a note value in the second.
The following mathematical formula explains how to determine the tempo before or after a metric modulation, or, alternately, how many of the associated note values will be in each measure before or after the modulation:
New Tempo/Old Tempo = Number of pivot note values in old measures/Number of pivot note values in new measures
DreamTheater does indeed use good examples of this smooth and intelligent transition. Drummer Steve Smith thoroughly explains Implied Metric Modulation in his DVD "Drumset Technique/History of the U.S. Beat". Terry Bozzio uses this, maybe Planet X. Other sources of help go to: