Originally Posted by
Kojak
"It's not nearly as noticeable as people make out."
This would depend on the tire. On the tires that the OP mentions, maybe you're correct. The lighter and more supple the tire (think racing or sport tires), the more noticable the difference. I'm not dissing Mr. Tuffys, just saying that you don't get something for nothing. If you add weight and a peice of rubber/plastic to a bicycle tire, it's going to feel different. This is true whether it's an add on (like Mr. Tuffy) or molded into the tire (like our Marathon Plus tires).
Please note that I said 'noticeable'. There might be a measureable difference but I'd suspect that it is vanishingly small. But perception is a very funny thing. You'd need a double blind test where the rider didn't know what he had in the tires. I've ridden both ways recently (700Cx23 road tires) and I certainly can't tell the difference in ride quality nor do I see a noticeable difference in speed.