That is the dilemma. Set up with 6lb line and a feeder for 5lb - 8lb barbel and some zoo creature makes a monkey out of you. Set up with an Uptider and sea reel and odds on a 2lb barbel nicks your bait.
I've had three confirmed large silure make off with my luncheon meat barbel / carp baits and the acceleration was phenomenal. Yet silure of up to 35lb have been landed with little fuss on a medium spinning outfit.
I don't know if you are aware, but one of the signs of a catfish in your swim is a sudden eruption of small bubbles. They are like tench bubbles that suddenly come up in a patch of around 2 square feet. It is caused by the swim bladder of a victim being crushed by the silure's hard mouth pads. Last time I witnessed this, I was margin fishing about 2 metres out and saw the damned thing take a double figure carp from the area I had baited up. It brushed my line as it turned and nearly took my rod with it.