The front side of each canopy has pretty similar characteristics. The toggle side of the Velo is more responsive than Katana. Velo definitely has more dive. My first 90s on the Velo 84 (2.25:1) were almost the same altitude as 270s on the Katana 97 (1.95:1). And even 90s were very, very fast. Velo is by far the most fun canopy I've flown -- absolute speed demon in a class on its own.
And of course with that speed comes responsibility. As much as I wanted a Velo, I had to pass. About 25% of all my skydives have been hop and pops (most from full altitude). I did a ton of full altitude H&Ps on my KA97 before trying the Velo, and all of my ~30 Velo jumps were H&Ps (most from full altitude). I also have a ton of speedflying experience. I'm very comfortable under a canopy, and under fast canopies. The Velocity really is a different beast altogether. I grew into it and really loved it when I had the sky to myself. But it was a little more than I was ready for, and definitely more than I was ready to fly into traffic -- something you really need to consider when downsizing.
I seriously doubt you've pushed your "Katana to the limits". Flying a small canopy in all weather conditions is a terrible gauge of your ability. Smaller canopies have less drag to be affected by the atmosphere -- they cut through the air better -- making them easier to fly compared to big wings. That's why paragliders and kiteboarders downsize when it gets windy. But a 720° to final downwind? Barrel rolls? Bailing from a low swoop? Getting back from long spots and holding your place in traffic? Using rears to eek out a little extra distance? Not needing rears after perfect gate entries? Not suggesting to go try those right now, but did you know it could do those?
When you've slowly, slowly, safely worked your way up to truly learning and exploring every parameter of your wing, not the weather, that's when you're ready.
BTW, for those who have moved to faster wing to "look cool", everyone at your DZ actually thinks you look like an idiot. It does not impress anyone to fly a wing you can't handle.