Hey, just spotted this post. Don't know if I am chiming in too late.
I will put in a plug for a modified-cooler mash tun with a simple steam infusion system.
1. It is dead easy to construct, and you won't need to contract a TIG welder to help build it (although I guess weldless fittings are possible).
2. You don't need multiple burners -- just one for the boil kettle, and perhaps something small for the pressure cooker (this could be an electric hot plate).
3. The system is lightweight, portable, and doesn't require a brew stand/sculpture. I use mine in my kitchen.
4. Heat retention in the cooler is excellent, so it requires less attention. And the steam system diffuses heat well, so heating overshoots are less of an issue.
5. The whole setup is cheaper than buying a keggle alone.
6. The 10 gallon cooler that I use doubles really well as a cheap fermentation chamber/lagerator (just add ice) and it fits a 5 gallon corny keg really well for parties on the deck! Multipurpose homebrew item!!