Another big difference is the lack of a rear locker and crawl control on the TRDP... do you go off-road much?
I'm assuming the 2011 SR5 is close to being paid off, if not fully yours already. Taking this deal will add $15,000 to your debt load and extend payments for a few more years. Is the new color and fancy grill worth it? Can your finances handle it? It's amazing what the lack of a car payment will do to your monthly budget.
And finally, what did you pay for the SR5 to start with? Take that value, subtract the offer, and figure out what it cost you per month. Then using the same value and mileage, figure out the cost per mile. Toyota 4Runners hold their value very well, especially with low mileage, so the offer may not be as great as you think. The dealer's going to wash/wax/vacuum it and list it for $33k or more.
Looking purely financially, it's probably a bad choice. You've got a perfectly sound vehicle with 200,000 miles left to give on which you've already taken the "drive off the lot" value hit and it's only five years old. In five more years, the value of the 5-yr-old 2016 TRDP will be more than the value of the 10-yr-old 2011 SR5, but will it be $15,000 more? As the owner of an older Land Cruiser you should know all this.
But it boils down to personal choice and ability. If your family income can handle it, and you want it, then go for it.