Hi Tinksquared,
For a little perspective, my mom (57, not much upper body strength, barely 5' tall) used my 2005 Sport this Summer on a very quiet stretch of river back in Virginia. She wasn't able to handle loading and unloading it by herself, so I took care of that. She absolutely loved riding in it though! She hinted that I should get a new one and she should 'inherit' the Sport, so I've placed an order for a 2015 Outback and will be surprising her with my old Sport at Christmas.
If she plans on taking it out on her own, my dad will most likely drive her to her loading location and let her peddle till she's tired and then pick her back up when she's ready because even the old Sport is too cumbersome for her to lift. It's not the weight so much as the unwieldiness of it for her to lift confidently. Because you mentioned you'll likely trailer the kayak, regardless of which model you get, that shouldn't be a problem for you. Also, the newer seats on all the models should be more comfortable for your back and neck, so you shouldn't be restricted to the PAs because of that.
As far as having a German Shepherd on the kayak with you, I have a German Shepherd/Golden Retriever mix that I wanted to include on my trips as well. The only problem is that there isn't enough room on the Sport (and I think you'd be pushing it on the Revos as well due to the shallow sloped angle of the well) for that. I could see him being able to sit in the well behind the seat in the Outback or on the PAs, but another thing you'll need to take into consideration is that even if the dog is well behaved and will stay laying down most of the trip, he will get HOT as the sun beats down on him back there. When I was growing up, I went on several float trips in a large 17' Grumman canoe down the calmer sections of the upper James river with my grandpa and his black lab, Prince. He was an EXTREMELY obedient dog and laid on the bottom of the canoe for long stretches of time, but if we didn't stop every now and then to let him out to swim around and cool off, he would have overheated. If you are dead-set on taking your dog with you, I would do a test run or two with him to see how he handles being in the kayak and to see if it's too much of a hassle, and only plan to take him out when the weather isn't too hot/humid.
As far as recommending a model, I'd suggest you find a dealer near you that you can visit to be able to see first-hand the dimensions of all of the available models. When you're looking online, it's hard to decide, but once you see them in person you'll quickly be able to see what you can and cannot handle. Also, if your dealer does any demo-days where they'll have some models out to test drive on a lake, pond or river near you, that would be ideal. At the very least, I'd see if they can bring two or three that you've narrowed your choices down to somewhere for a test before you buy...these aren't small purchases and that little bit of customer service I think isn't too much to ask. After all, you wouldn't buy a car without a test drive, would ya?
Good luck with your decision and I'm sure you'll have a blast with whatever you choose!
-Dan