I went through the 1/2ton SUV buying choices last fall when I bought my Sequoia for a family hauler, TT tow vehicle & Colorado byway adventure rig. I tow a Nash 22H (5K empty) with an Equalizer hitch. I need to get on a scale with it loaded, but I suspect it's about 6K loaded. The interior, powertrain, and four wheel drive capability tipped our decision to the Toyota. The payload is indeed a drawback, and we chose to favor the first three and buy a smaller TT to deal with the payload. I searched a lot of threads on here, and was helped by some great posts by a number of Sequoia owners, including "Drbolasky" who has weighed in here as well.
I've towed my Nash 22H (5K empty) with both my 2011 Sequoia (5.7L, 122" wheelbase) and my 2005 F-350 (V10, 173" wheelbase). The Sequoia with the Equalizer is more stable and gets better mileage by 1-2 and delivers better performance. For anyone familiar with I-70 west of Denver, my combo can make the speed limit on any grade there. Due to the gearing and lower curb weight, the Sequoia can outclimb my 3V V10 and is much quieter doing it. Of course, that's not all the story but just one data point.
2005 F350 SRW V10 4.10 CC LB 4x4; BW Turnover ball; LineX
2011 Sequoia 5.7L 4.30; Tundra Towing Mirrors; LT 275/65R18 C Goodyear Wrangler MT/Rs on 2nd set of wheels
2005 Nash 22H TT