We just tore the back off the house and building a new kitchen, 2 bathrooms up and down and a new laundry/utility room. It is a 100% re-pipe of gas, water and soil pipe for the whole house and I'm running Uponor Aqua-pex throughout. I've had the manual "expander" and it worked fine on 1/2", was tougher on 3/4" and freakin' impossible on 1". You have to be Godzilla to pump that thing by hand. 30-40 yrs ago, maybe okay. All of this effort X5 if you are doing an "in-position" joint. So, I bought the new Milwaukee Expander and pex is a piece of cake with it. I was under the house in a tight crawl space and was able to do the 1" joints with no problem. I've rarely had a tool purchase make such a profound difference in speed, quality and just plain satisfaction.
I have no problem with the manual expander when doing 1/2". 3/4" is ok too, if I can get on the joint. If in a tight spot the 3/4 is tough to handle...for me. YMMV! The hand expander works fine.