Haven’t used one live yet, but have played with them and will be buying a 400 in each speed shortly.
Keep in mind that this is really a replacement for the Curado 300 and it will not perform the same as the Tranx 500 in a smaller package. And the only difference between the Tranx 300 and Tranx 400 is spool width/capacity.
The Curado 300 was an incredible muskie reel in its own right: fast, easy to hold, and bombproof…so upgrading the features with their new technology and adding an even higher speed version for the Tranx 300/400 should make for an incredibly nice reel for jerkbaits, rubber, topwaters, and burning small blades. I don’t see it being a “smaller” answer than the Tranx 500 for big bucktails, as there’s just no getting around the physics of line/crank. These new reels have high line/crank accomplished with high gear ratios, so hard-pulling baits will still be tough. Everything else though? Game on.