The majority of the wood framed windows i replace is Anderson first and foremost since when folks are having homes built they "trust" the name since it's been brain washed marketed into them, so by far the ratio of replacing wood windows, andersons are the clear winners. Pella is a close second place due to people having a slightly larger budget or realizing windows are not the area to chince since they have to be able to do soo many thing other than open and shut to allow natural air in the home.
The problems I am seeing with the Pella Aluminum clad units is mitering actually seperating on exterior side, often the worse windows typically end up on the south side of the home so extreme sun exposure/heat build up is playing into the break down. The miters are cracking just enough to start allowing water to trickle in-obviously at a slow rate-but enough to start slowly saturating the interor of the window, so in essence it's a slow process of rotting from the inside out. The first clue to this is often discolored wood on interior side, often the grain will start turning a greyish color and I've also seen cases where small little "sandpaper type grit" forms under the interior finish coat. With the windows in question the seals appear to still be in good repair, often the andersons and once in a while the pellas will get hard/stiff and not provide the same sealing it did when new. Have also seen quite a few of these 2 mentioned brands with hardware failure. Naturally as you know/all of us know, on casements/awnings 90% of the failures are due to customers over tightening when closing and stripping teeth off the gears. This will happen with any window so I'm not saying that is brand specific.
I've just seen a number of the "clad" windows have exterior failure which leads to the rotting process-vinyl cladding being the worst. Almost every warranty I've seen does not guaruntee "caulking" so there is the upkeep part homeowners are responsible for, when these exterior joints fail it's up to them to silicone them to prevent water infiltration, I dont like maintenance and neither do many customers so I make a point of selling maintenance free windows when possible, but like any of us I will install whatever the homeowner wants since they are footing the bill for materials not me.
I've noticed also on homes built 10+yrs ago, the window's glass coatings must not have been upto snuff since stools are stained from faded/dry rotting due to UV exposure, not to mention the curtains, bedspreads, furniture, etc...all show terrible fading. Some of the rotting is homeowners fault for having interior mositure to high and windows sweat excessively and then the water trickles down onto stool. We all know every instance has it's own unique circumstances. But after swapping out windows for more years than I care to count, and seeing the after math I'm just not sold on wood being a long term solution for windows/doors since I see what happens long term. There are better materials out there for folks that dont want to change their windows in the future so that's what I try to convey to folks.
Besides, I've installed my windows in 2 Pella workers homes-they are acutally service techs that travel around the midwest repairing Pella problems, and after hearing some stories I knew why they contacted me

Price was a huge factor along with minor "thorn in your side" type problems. One things for sure though, Pellas loves their windows $$$$$.:w00t:
Personally been selling/installing Heartland's 700 series windows for over 14yrs, the warranty is great, should a problem ever arise it's rectified swiftly by sales reps. There are a number of other brands I've installed over the years and Heartlands have given me the best "no headaches/no return visits" over all the others so for my own sanity I've stuck with them obviously. There are a few other brands I would like to try, but unfortunately i have'nt met the homeowner with the deep pockets to afford the $5-700 double hung price, and that's just window price

so we'll wait and see.
But like you've already said, proper installation goes ALONG ways. A typical home builder using the common low dollar help only cares about speed and often quality suffers, so you can have the best product in the world and if not installed right will turn to crap. But take a half shoddey product installed by folks that give a ******************** and it will almost always outlast the best installed by hacks.