I would go with the Shimano Baitrunner 6500 B - be sure you get the ARB version (anti-rust bearings). These run around $120 or less depending on where you look.
IMHO this is the best BR reel made for normal people.
Thunnus are nice, but they cost over $100 more. The front end of the reel is identical to the Thunnus except for the color. Internally they are different, but the std Baitrunner is so tough and well made, offshore tuna guys use them all the time w/ 25-30 lb mono on them.
FYI - charter buddy caught ~70-80 BFT on his Thunnus last yr and had to send it back to the company to get it repaired.
He was a little PO'ed needless to say - I think he said he bent the shaft on it. Typically he uses 50 lb Spectron and is sight casting to moving school tuna.
One feature the Shimano does over Penn is when you crank the handle the baitrunner features kicks off. Penn you manually depress lever/paddle.
That St. Croix is a well made production rod. I picked up a 8.5' - 2pc Premier and like it a lot. Their Avid series is nothing to ignore either. They made some improvements the past couple of yrs and it was for the better.
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