Well, you get a
Push/Pull power out of them, kinda like a kevlar clutch, no slippage (even with clips you lose a small amount) When Look pedals 1st came out, and I got a pair back in the 80s, I couldn't believe the difference from clips. On a BMX track (I still ride flats) there is a big difference with riders with & without, so much so, that most have switched to it, only old farts like me, bitterly cling to our Bear Traps
Yes, you will get a more well rounded leg work out. There are others who can answer this better than me.