Well they are both made quite well. Good machine work on both. The only real difference between the two are the 3 cylinder and 7clinder. The Saito's 3 cylinder has a more Throaty poping sound from the larger cylinder volume, where the UMS has a constant rumbling from the 7 cylinders. The UMS is quieter than the Saito, I believe it is from the smaller cylinder volume, but sounds more scale to me.
It sips fuel a 24oz tank would be more than enough for a 15-20 min flight.