Welcome along as our hosts here like to say.
Lime is definitely deferent than gypsum when it comes to mixing and spreading. You also won't be building work out much and if you overwork it on the wall you'll start to delaminate pretty bad.
That said it's not too bad once you get used to it and figure out what you can and can't do. I'm assuming this is an exterior application correct? I haven't used US Heritage but with a name like that it has to be great... maybe I should give it a try .
Last lime project I did was with NHL and like was already mentioned here that stuff is annoying to work with. You have to mix much longer than normal. My mixes were always very wet for about 15 minutes and then the lime would finally catch up and suck out the moisture and make it workable. Thin coats are your friend and don't over work the material on the wall. Measure out your water and follow the mfg recommendations as close as possible. Hope it goes well!