I swim and I do not find any increased pain from it at all. Actually I'd think being a little more flexible would make you hurt less since you've got more elasticity in your muscles to absorb the shock.

Would that be right Scrap or am I blowing smoke out my ass?

I also don't have any shoulder problems or soreness or tiredness unless I swim very often or very long. Used as a cross training tool with all different strokes 3 or 4 times a week, having eased into it gradually I can see any issues arising at all.

When I don't get to the pool it's more for logistical reasons sine I have to travel to get there and don't have time to get there and back in my lunch break. It's not as easy to fit into a busy lifestyle - that'd be the only real drawback i can think of.