Yes two wheeled pieces is unwieldy. Don't do it. Well, there are "train connectors" that allow you to daisy chain several wheeled pieces but I've never tried them and suppose this is only good when there are absolutely no curbs or stairs.
Checking a duffel bag is absolutely no problem, as long as the bag is well built, the contents not too fragile and well packed. I've done it many times.
If you want the best volume to weight ratio, choose a big wheeled duffel bag like the Eagle Creek Super ORV. Chances are you will not need a second bag.
If you do need two bags, a wheeled piece is still the way to go. Get one wheeled and set a duffel bag on top. You can fit a duffle on top of a 28" suitcase that would also be too big for the cabin. So you have two must-check pieces that are transported together. Additionally, choose a wheeled bag that has a removable J-hook or other type of extra luggage attachment. With this you can dangle a third piece (like a briefcase) on the front, while the duffle is riding on top.
This will allow you to transport three bags and up to 50kg with one hand. Pretty efficient if you ask me.
I concur with ABB in that soft luggage plus trolley for checking is a hassle. Soft plus trolley is good only if minimizing luggage weight and maximizing space is the top priority and wheels are still absolutely required. In that case buy an A. Saks 21" Exp Tote and a Samsonite Micromover Cart. Done.
Welcome to FT, Henry!
Till
P.S.: @ABB If you know how to fold and pack your stuff properly a hard bag is not needed to keep even suits and shirts wrinkle free. Check the packing sticky on top of the page for details and how-to's. It takes all of ten minutes to learn. There's even a video.