I'm thinking the heavy steering may possibly be caused by the trim tab on your motor needing some adjustment. It's a small fin that hangs down just above the prop and can be adjusted either direction to relieve the torque you feel thru the steering wheel.
Loosen the nut and adjust the angle of the fin a SMALL bit, then tighten it and go for a test run. You'll probably need to adjust it several times till you get it right, but if that's the problem you'll notice a big difference in how the boat steers.
It's been about 10 years since I've had to adjust one and honestly can't remember which way to go, but it seems to me you turn the fin in the same direction you need to turn the steering wheel to fight the torque....I think.
As for hydraulic steering, it's excellent. I've got it on my 150 Yamaha and am very impressed with how easy it is to steer and as mentioned above, there is absolutely no torque at all, no matter how fast your going and is very similar to steering your car.