The Lasers are, hands down, the best engines commercially available, IMO. That opinion is formed from 17 years of using various brands of model engines. I have a 150, but they all are pretty much similar in construction/operation.

They are designed to run on no nitro. Up to 15% will improve the idle, but WILL NOT give an appreciable increase in top-end power. Anything over 15% is simply wasted. It will not hurt anything.

They have less power output than an equivalent Japanese engine. The 70 will be equal to a 50-52-56 OS/Saito/Magnum; IOW, a 40-sized plane. My 150 is equal to a strong Jap 120.

So, less power; but your reward is an utterly reliable engine. If you want Saito 72 equivalency, you'll need the Laser 100 or 120.