I may be off my meds but I still do not think the upgraded shingles are worth a penny more. For example what the difference between a timberline 30 and a timberline Ultra? Well one is thicker and has a higher wind resistance. That's a fact, but both will last about the same ammount of time.
What I mean is, in my area the average life of a roof is about 15 years. I have read reports of 12 and all the way up to 17. Roof are replaced for more reasons than them failing. Did you know the average family moves every 7 years? Quite often a perfectly good roof is replced for no other reason that the new owners do not like the color. I've done a few of these myself. So the point is your roof will probably be on your house an equal ammount of time if it is the 30 or the lifetime.
NOW let us discuss the exception to this rule. There is an exception to the rule, and you will see above I compared almost identicle shingles, the timberline. Now let us compare the timberline 30 to the GAF Grand Sequoia. The grand sequoia is a lifetime rated shingle. Who cares? I certainly do not... the LOOK is beautiful IMO. In this case you'd choose the lifetime shingle because it LOOKS much much different and unique when compared to the timberline... you wouldn't choose it due to it's warranty or iwnd resistance.
When my customers ask about upgraded shingles I give them my professional opinion, and my professional opinion is as stated above. I also tell them that there money is spent on better upgrades such as underlayments, ventilation or flashings instead of shingles. MOST of the time they respect my honest since alot of salesmen walk in the door trying to sell them the most expensive.
Not to strech this post out any further, but also keep in mind I do not sell the junk materials. No 20's on my roofs.