Freefuel, the factor that determines the operating speed range and limit is not so much the number of cylinders or the cylinder arrangement, as the stoke length of the engine. The inertial balancing method does help, but mostly long stroke engines reach maximum allowable piston speeds at lower RPM. Inertial loads of reciprocating parts quadruple when you double the engine RPM for a given configuration.
Consider a model 2-stroke engine with a .75" stroke running at 15 to 20 kRPM. Consider a Ferrari V8's rev to 9kRPM, despite their "flat" crankshaft to even out firing pulses at the expense of inertial balance. This is possible because Ferraris use large bore to stroke ratios, or more specifically, short stroke engines.
The same principles apply to diesel engines, except that peak power speed for a 2 liter 4 cylinder diesel may be 4000 RPM, while that of a truck diesel may be only 2000 RPM due to its longer stroke length.
Research power band and redline RPM VS stroke lengths, and you will see what I mean.