Variable tooth blades (such as the 10/14 you mentioned) generally have 3 of the 14 pitch teeth, then one of the 10 pitch teeth, repeated for the entire blade. Likewise with 14/18, and 18/24 variable toothed blades. I've never had good luck with the variable tooth blades....what always seems to happen is that just as the blade gets "broke in", one or more of the larger pitched teeth will break, causing a terrible "Thump" and "grab". Usually, once a single larger pitch tooth breaks, others quickly follow, and shortly the blade is wrecked.
I'll second that, Ed.
Variable-pitch blades are often misunderstood. They perform well when used in the intended application, though.
The variable-pitch was designed for a specialized application- to lengthen blade life during interrupted cuts in metal. Interrupted cuts meaning those cuts where the blade may be in contact with more than one cutting surface at a time; e.g., pipe, tubing, channel, I-beam, or angle (if cut at other than a right angle). IOW, structural steel.
These types of cuts introduce severe harmonic vibration to the blade, and the variable-pitch is designed to help tune out that vibration. So the intent is not to affect the quality of the cut, but to lengthen blade life during those types of cuts. Lessening the vibration increases the amount of time before the blade breaks due to fatigue.
The problem is that many people use the variable-pitch as an "all-purpose" blade, and sooner or later a solid piece (e.g., flat stock) is cut that is thinner than what the coarser part of the pitch is designed for, resulting in a broken tooth. And we all know that one broken tooth leads to others.
I have spent a lot of time (and $$!) sorting out the "ideal" blade for different applications. I have one wall of the shop filled with different blades hanging from it, and another shelf is filled with differing coil stock.
There is no "one size fits all". Yes, we can get the job done with something not particularly "ideal", but the tradeoff is either poor quality cuts or decreased blade life.
Constant-pitch: Used for all flat stock and smaller barstock. Examples include initial profiling of knives, steel strap, plate, etc.
Variable-pitch: Used for all structural-shaped steel, and some of the larger bar stock.
Examples include BossDog's NWGS, stands or frames, or any other application where an extended interrupted cut is possible. Basically any application calling for use of structural steel.
Also, I have experienced longer blade life using variable-pitch on larger solid bar stock.