I've been restoring a small old wooden building for the past few weeks, and have been putting some pretty heavy hours on this Porter Cable 3x21inch belt sander, model PC352VS. The bulk of it has been removing paint from timber after having heat stripped it. I've also done a couple of doors inside and out. Probably 30 hours or so on it in the past couple of weeks I'd say.
Tracking Adjustment: sorta sucks - you kind of get the hang of it after a while, but when you turn it a little the belt continues to drift in/out after you've stopped turning so you have guesstimate how much to twist the nob. Also, the belt seems to wander fairly easily - requiring frequent readjustment of the tracking.....which sorta sucks.
Power cord: doesn't bother me at all coming out of the top like that.
Dust Collection: the location is not a problem at all - just spin it around if you need to. Now the acutal efficiency of it is a bit suspect. When you sand, for example, a table top, it seems to do pretty well - I don't really notice too much flying dust/debris. I'd say it probably only gets maybe half of the overall waste (maybe). When you sand holding the sander above you or at shoulder level, you really notice the sh** flying through the air, and it seems as though it bags just a small fraction of the total waste. Overall though, if you wear a good mask and eye-protection, I'm comfortable with the dust collector. It's easy to pop on and off and easy to empty.
Overall Power: this is a tough one to answer, as I've definitely been able to make it bog down when I really lean into it. However, when you're belt sanding at chest/shoulder level for hours at a time, you'd probably prefer not to be lugging *too* much weight around. This unit weighs 10.75 pounds. I'm a pretty fit 5'10" 170 and believe me I feel it after a while! The next step up (if you want variable speed) is the 3x24inch 360VS at 13.5lbs. This has a 12amp motor vs. 8amps on the 352. Not sure what it all means, but there are times when I'm flat sanding when I wish the 352 had a little more oomph, but vertical sanding it feels pretty good to me. You really need to figure out what you'll be using it for mostly. If I were to have just one BS, I'd think hard about a bigger unit.
Balance: I've heard some complaints about the motor placement, but I've had no trouble keeping this unit flat. Even one handing it.
Size: I sort of feel like a longer platen would be much better for flat sanding, as when you approach an edge you need to be pretty careful of rocking. If the bulk of your use will be flat finish sanding I'd go with a longer unit.
Belt Change: Simple and quick with one lever. Tracking is another issue though.
FINAL THOUGHTS: If you only plan on getting one belt sander, I'd go with a bigger unit. I'm happy overall with it, as it's serving a purpose for me right now. But it's just a little small and a little underpowered for me, and the tracking is annoying. My verdict is if you're a smaller guy doing a bunch of vertical sanding, this is a good unit. Otherwise I'd go bigger.