Adding on for other people that may be in same situation:

Its not exactly an apples to apples comparison... but somewhat close:

I have four pieces of salsa deluxe (1 IATA, 2 Cabin Spinners, and 1 26inch)

I also have the Topas Sport 80.

Two of the carry on's get used at least weekly, mostly for u.s. domestic air travel. The 26 inch and the Topas Trunk gets used every 3 months for international travel. The Trunk exclusively carries SCUBA gear.

I have had zero issues with any of the salsas. They get checked frequently on return flights, and get dragged around lots of urban areas (NYC streets and subways, etc). They hold up to scratching pretty well too.

The trunk is a different story. It usually has between 50-70 pounds in it and takes a serious beating. Every trip has a new dent in it. I love that part of it. After two years of use, it looks like a beat up aluminum can with stickers all over it. Lots of character.

However, I have had some items break on it. One of the wheels sheered off from luggage handling, one of the velcro tie down straps cracked, and one of the combo locks was ripped off. All were replaced by an email to rimowa service free of charge. For the wheels, they actually sent me a few extras too. Takes 60 seconds to swap one out.

So to answer the question directly, if dents and such are a concern, consider the polycarbonate. If you overpack and check, i'd forget about the watertight seal as the frame will eventually bend a bit and the rubber gasket will get chewed up too. Also the zipper will structrually support the closure all the way around versus an overstuffed suitcase holding it in three spots. Having said that, i've never had a problem with the Topas popping open.

The Salsa Deluxe has two of the flex dividers (which are fantastic) and come in the glossy colors. It also has the add a bag feature (I use it but always am concerned its going to pop off, which it does if a lack of tension occurs in the strap... also concerned my carry handle is going to fail but it never has)