I contend that filters do nothing to lengthen the life of a piece of equipment. They DO lengthen the service life of the lubricant! It's a subtle but important distinction. Think of it this way; which one is a necessity, and which is a luxury?
Can you run an engine with no filter, but good oil? Sure. Your engine could last some reasonable amount of time with no filter at all, but run on a decent oil. (Think of all the small engines that have no filter at all, including marine engines too). Only after the oil gets saturated to some point of condemnation would it start to degrade, and become overwhelmed by contamination, and the result would be engine damage.
Now, consider the opposite situation. How about putting on a premium filter, but running with no oil? Damage is immediate.
Filters directly affect the lifespan of oil, and oil affects the lifespan of the equipment. But filters have an INDIRRECT affect on the lifecycle of equipment.
If you change oil often enough, it's likely you'd never need a fitler. You would be removing the contaminants via oil exchange. Filtration only prolongs the life of the lubricant's useful lifecycle.
That being said, a premium filter can be made to achieve a few things, but I still believe Gary's filtration triangle theroy is fairly sound. Size, lifespan, and efficiency are inter-related; hold one characteristic constant, and the two others become inversely proportional (or nearly so). You can certainly argue that efficiency is affected by the percent of saturation (more efficient as it ages), but overall, we're debating the mundane and nearly silly.
I look at filters the same way I look at oil. If you want long service, you have to pay for upper end products. "Normal" OCIs can easily be handled by dino oil and traditional average filters. Extended OCIs call for synthetics and/or premium filtration. If you match up your products, you'll get good ROI. If you mis-match, then you're wasting money somewhere.