Yes, your comments definitely help! You raised some good points which I hadn't thought of. I'm certainly not against doing laundry, and that's something I always have to do while on holidays, either just rinsing a few things out in the sink, using a local laundromat or in some cases the service wash offered by the hotel. I'll have to give some further thought on the "shape" of items that I usually pack.
The capacity / volume of the TriStar and (for example) the Pilot would be about 18L less than the 64L Backpack + Daypack that I'm currently using. That would provide me with some incentive to pack lighter, but that's something that will take some thought and planning.
Thanks for the comments. My travel is only for leisure purposes these days as I'm retired, but I'm sure the TriStar will be good for that also. Unfortunately, I haven't had an opportunity to travel with it yet, as I only bought it at TB headquarters during a trip to Seattle in January. Hopefully I didn't stay too long and annoy the guy working in the shop, but I wanted to see everything (fortunately it wasn't busy that day).
I should mention that I decided to try the TriStar after using a similar bag from another well known manufacturer. Although the other bag was superb quality, I found it too large and cumbersome even when "reasonably" packed. There's no way it would fit either the bins or underseat on DH-3 and similar aircraft, so I usually just placed it on the á la Cart wagons (Horizon Air term) outside the door of the plane.
I find that regardless of how much time I spend looking at luggage or other items on the web, I always like to see them in person before making a purchase decision. I walked into the TB shop that day with the intention of buying a Western Flyer, but after seeing the WF and TS side-by-side, I realized that the TS was the perfect choice. Once that decision was made, I had to decide on Solar or Iberian for the interior, and pondered that question for awhile while looking at other items (I finally decided on Solar and I'm happy with that choice). I also bought several other items and was impressed by the quality and attention to detail of all of them.