While intuitively, one might think that ease of use = less tight fit, that doesn't necessarily translate in the real world. The Paradigm probably has the better air number is many cases.

Is there anyplace on line where I can compare the U factor and other #s for a variety of windows?

+1.

NFRC.org is the resource that you are looking for. On the plus side, it's about the only resource for comparison that is truly unbiased. On the negative, as WoW alluded to, it can be difficult to navigate and there are MANY product choices. You would really want to obtain a CPD # and plug it into a certified product directory search to make sure that you are comparing correctly.

schreibdave, curious what your final decision was. Did you choose Paradigm? If so, are you happy with them?

Went with a different builder so no on the Paradigms. This will be an unpopular comment here but we went with the builder grade Jeld Wen single hung. Honestly i am quite content with them.

Very unpopular!

We are on a budget and my tract builder was really going to gouge me for selecting anything but his standard product. So we crossed our fingers and went with it. The windows look fine and the house passed the blower door test with a 1.7 ACH per hour. So the windows are air tight enough for my needs.

Hopefully they were well installed and won't move around much over time. I am not sure if we can really separate out how much of the issues with windows (i.e. most new construction and production builds) are due to install vs. substandard products.

Clearly there is a contingent of both, but if a mediocre window is well installed, it "should" work properly.

Hopefully they serve you well and for years to come.

If they were to stop operating properly what would you expect to see? The window become out of square and not open/close properly? Bigger clearances between the frame and the window? These are pretty flimsy so I could see how they would not resist movement in the framing very well.

Yes, all those.

+1 to WoW's comments. Even the worst windows will not seem terrible on day one, or even year two. Generally, better windows will have fewer QC issues off the bat, have a more substantial look and feel, and will also be easier to install to ensure proper operation and performance. That said, sitting on this side of the equation where we not only replace 10-12 year old builder windows regularly, but have to service the windows that we have sold 5, 7, 10+ years ago, that is where the products really tend to separate themselves. Excessive seal failures, bowing sashes, broken parts, etc... I truly hope that your windows serve you well for a long time schreibdave, but once you push 10+ years you are beating the odds at that point. That may sound like sour grapes but the fact of the matter is this: I could sell exponentially more jobs by using a cheaper product at a lower price point, however after X years I'd put myself out of business trying to service them. Builders on the other hand aren't fielding calls on they cheap windows that they put in in year 10, so they can get away with that type of thing.

I can see that being the case.