Can anybody explain / speculate as to why the fork offset on a trek 520 is 52mm? It seems like a lot to me since common fork offsets seem to be 43mm or 45mm.

I don't ride my trek 520 much because it feels like I'm driving a bus. Between the 71 degree head tube angle and 52mm fork offset it's almost like riding a chopper. Would replacing the fork with a fork with less offset make the bike feel more "sporty"?

It is designed to be stable when loaded, hence the slow steering. Also, in a non-suspension fork, the large offset increases ride smoothness, another goal. The long wheelbase works toward these objectives also. All of them reduce sportiness. If you want "sporty", buy a sporty bike. The 520 was primarily designed to tour, a different objective.

As the head angle is reduced you need more offset to achieve the same trail. If you reduce the offset you will increase the trail which will make the steering even slower. Perhaps it is a cyclo-cross bike that you want rather than a tourer if you travel light.

Yes, I've been debating whether or not to get rid of the 520 and buy a lemond poprad. The poprad while not ideal for touring may be ok. I'm driving myself nuts trying to decide. I definitely would like a more sporty ride but would like the option of doing a loaded tour also. I probably can't have both.

Loaded touring bikes need a lot of stability. If the slack steering bothers you then by all means get a Poprad. You need to beware that your rear pannier may hit your heals so you'll need to use bags that have heel cutaways.

In general a Poprad makes a great all around bike. AND as an added bonus feature, the 2006 models are ORANGE! When I build up old bikes I like to paint them Molteni Orange from a rattle-can. That's got to be the in-est thing in the sport.

I don't think that I'll have a problem with my heels hitting the panniers. Last weekend I put my panniers on my trek 1000 which has 41.7cm chainstays. With the panniers all the way forward my heel just grazed the bags but I was able to slide them back a little and had no problem. I suspect that I wouldn't have a problem with the poprad an its 43cm chainstays. One thing that bothers me about the poprad is that it doesn't have eyelets at the top of the seatstays to attach a rack. I'd have to use some clamps or rig up something to attach to the seatstay bridge.

I like the orange too.

You can get the clamps from Rivendell, Bruce Gordon or Tubus. That's the least of your worries.

https://www.peterwhitecycles.com/tubus_racks.asp
(near the bottom of the page $6 for brackets)