Hey Andrew
I own one of these, and have done for nearly three years.
They are definitely faster than an eggbeater, (I also own a Shimmy 6500 baitrunner), cast further, and work hard.
I've got mine strung with 14kg braid without any problems.
Don't know about tuna, I work mine in the surf tossing poppers and metal, and the retrieve is definitely faster than anything else on the market in my experience, and if tuna requires this you can't go wrong.
I used this reel as a winch, jig fishing for big salmon off Vancouver Island in Canada's Pacific Northwest, caught a 9 and 11 kg silver, reel performed effortlessly, the drag is excellent.
Good reel.
Hope this helps.
ReelCrazy