3.5g Unique will be a light recoiling load along with sooty cases, unburned powder and lots of smoke. Without buying new bullets, you can get lower recoil by using a smaller charge of a faster powder (no, not Bullseye, it will behave like Unique at those low pressures).
2.7 to 3.0g Red Dot/Promo/Clays/Clay Dot/Titewad/Extra Lite will get you about 750 fps with a 180g bullet which is just about the same power factor as a 120g 9mm bullet at 1100 fps. For me with my M&P 40, it gives a very low recoil, fully functioning slide and cases that fly 1-2 feet out of the gun. When I replace the 40 S&W barrel with the 9mm barrel and shoot the 9mm bullets, the recoil feels exactly the same. Same gun, same slide & spring, just different barrels, magazines and bullets. That's about as close to an A/B test as you can get.
Momentum is the equalizing factor (bullet weight X muzzle velocity). That's why competitive shooting is so focused on power factor to try to make the playing field equal.
A fast powder will expand the case, seal the gases and give a clean burn without driving the bullet out too quickly. Slower powders need bigger charges to get that pressure up which also drive the bullet out at a higher velocity -> more recoil.
Hope that helps.