I have printed at 240 for 18 hours with no real degradation of the liner.
I am upgrading the print head right now to a MK10 and using high-temp capricorn PTFE, which has been said to have a working temp of 250C and a peak usable temp of 300C, it takes two minutes and $0.10 to change a tube, which makes it able to print most everything but PC and high temp nylon (but then you also need a hood and filament drier on board)
I don't like all metal hotends, retraction and temps get really touchy when printing anything low temp, and while the E3D V6 works well as a all-metal hotend (I have one on my delta) you will lose over 25mm (or more) build space.
I'm also kicking the ramps 1.4 to the curb and installing a Duet 2 as the Ramps setup works, but when you have multiple items printing or very complex models it struggles to keep up, I get juddering artifacts when printing 10 items at once.
It's also worth mentioning that I installed a $10 mosfet tube for the bed heater, this offloads the current in the board.