I currently own a Chute 3, and have been diving it since 2004. When I'm diving with a single tank, I'm using the Chute 3. It has almost 200 dives on it, and barely shows any signs of use. (The tank band is slightly worn at the closure.) This is a heavy-duty BC with 4 nice solid pre-bent D-rings from which to hang stuff. The major drawback is the inflator / deflator mechanism. On several occasions, it has either stuck open while inflating, or not vented properly upon deflating. (Hint: disconnect the low pressure inflator if the button gets stuck, and be prepared to pull the rear dump if the deflator isn't playing nice.) While I have not done so, it would not take a great degree of effort to replace the inflator / deflator with something more reliable.
When I first saw the Excursion earlier this year, my first thought was "What happened to the Chute?!" The Excursion's D-rings are definitely less "manly," and there is some sort of padding added around the neck area. There are some slashes of grey around it, where the Chute is all black. The deployable pocket is also slightly different, but for some reason they still have not brought back the side pocket from the Chute 2 that everyone misses a great deal. It seems like the Excursion may be somewhat lighter than the Chute 3 (the Chute 3 is not a travel-friendly BC, so plan to leave the bulky integrated weight pockets home when you travel with it).
Beyond these minor modifications, it appears to be almost exactly the same back-inflation BC as the Chute 3.
The major difference is, as you pointed out, the price. The Chute 3 is available from about $299. The Excursion is still in the $600 range. (I originally bought my Chute 3 for $625.) It might be "nice" to have the latest available product, but I don't think that extra money is buying you anything beyond what the Chute 3 offers. I dive mainly in Jersey in some of the most challenging conditions, and the Chute 3 has served me well all over the world. I suspect it'll serve you well also.
I have the 45 pound bladder. I'm 5'9", 165 pounds. At most, I use 12 pounds of lead with my 7 mil in freshwater, 18 pounds in saltwater. I use the Chute 3 with aluminum 80s, steel 120s, occasionally an aluminum 30 stage bottle. You may want to do some math to figure out which bladder will work best for you and your diving needs.
Andrew
PS - My initial reaction to your weighting situation is that you're carrying too much. If you were my student, I would re-evaluate your situation and make sure you're properly weighted before basing a bladder purchase on the amount of weight you're currently using. I don't know you, so you may be spot-on, but I did a doubletake when I saw 26 pounds with a 7 mil.