Too late to help now but maybe someone else will benefit. I gel stained my Pella fiberglass entry door 6.5 years ago and it looked great! Used Minwax gel stain and their spar varnish, as directed by Pella. However, it did not stand up to weather at all. It chipped and had to be varnished again every 6 months. This Spring it chipped all the way through to the fiberglass and pulled stain with it! Believe me, I did everything properly. My door faces south east and has no roof. But a neighbor whose fiberglass door faces north had the same trouble - he used the same products as I. My neighbor got disgusted and stripped his down to fiberglass and restained it with Sikkens products 3 years ago. No trouble since. Sikkens makes a Door and Window stain that does not require varnish over top. Fortunately for me, just before I started stripping about 36 layers of varnish off my door, it delaminated! Pella brought me a new unfinished slab (under warranty) and I'm using Sikkens to stain it. I've been told the varnish is the trouble. It's like putting a sheet of glass against the door, trapping the heat. Plus it isn't flexible enough to expand and contract. If I put up a storm door to protect it, the problem would've been worse due to trapped heat. Sikkens is specifically made for fiberglass doors. I don't have any vested interests in the company but thought I'd try to help the next guy... Here is a link that might be useful: Sikkens Door and Window stain

I did my ThermaTru door with Zar gel stain and Sikkens D&W in Sept 2009 (thanks to Faron for recommending it). Should have recoated last Sept but didn't - I'll do it this spring once it warms up. The bottom of the door is a bit faded - hope I don't have to strip, it's not peeling. Top is shaded by porch so the bottom is the only part that gets direct late-afternoon (west) sun. Does D&W expire? I haven't checked the can. Sikkens changed their website, don't see that Cetol 23+ or D&W have been discontinued. You can search for a dealer in your area. I didn't find the paint store where I thought I bought it (Ben Moore) but looks like Home Depot is carrying the line - maybe they can special-order for you? Here is a link that might be useful: New Sikkens website

I have a Pella fiberglass entry door, installed 6 years ago. I would disagree that using gel stain is the best way to go, in fact I wouldn't recommend that at all. It looked beautiful when I finished but required varnish every 6 months. Even then it failed miserably this spring. Don't do that, there is a better way. Fortunately, or not, my door delaminated this past month. Fortunately because I was about to strip it and start over again. As it is, Pella provided me a free replacement slab since it is warranted for 10 year. This time I'm using Sikkens Cetol Door and Window stain which does not use a polyurethene varnish topcoat. I found out about it from my neighbor who had the same problems as I with a gel stained/varnished entry door - chipping and peeling varnish. He redid his four years ago with this Sikkens stain and it looks great even now, with no further attention. Sikkens does recommend reapplying one coat after 3 or 4 years but that beats varnishing every six months plus it doesn't chip away like spar varnish. Use Sikkens Door and Window stain instead of gel stain and varnish, seriously. It comes in four or five colors but you won't find it at HD or Lowes - go to their web site and find a paint dealer in your area. Here is a link that might be useful: Sikkens Door and Window stain

Lots of factors to be included in the opinion. Things like which direction the door faces. North facing in winter get punished by cold/snow/etc. South facing doors get heat in summer, South facing fiberglas doors have been known to disfigure due to excess heat. Storm doors can help or hinder a doors longevity. Pros of wood doors: Lots of different natural colors. Lots of intricate details possible. Strength is usually high Cons of wood doors: Wood moves with weather(temp and humidity) Wood has to be finished(painting hides the grain. Clear finishes have to be periodically renewed) Wood doors are heavier. Wood door parts can separate due to weather. Real wood doors are much more expensive that clad doors. Fiberglas doors are simply wood cores covered in a fiberglas shell. They can have asimilar look to wood, but have to be painted/stained to have a grain pattern. Like vinyl siding having a texture like wood but the look of plastic. I have steel doors on my house---wood cores with a steel cover.