Like Kuraki, I use an impact on mine as well. It's not that I can't reach, but it makes it a lot quicker and easier. I had bought a HF butterfly impact to make a power drawbar attachment similar to what Saunders Machine Works sells (not sure if they still do or not), but I ended up just using the impact and not making the fixture.
If height is a limiting factor, I'd probably just make a little riser/step next to the machine and stick with the R8 with an impact, but that's me personally. You might also find a power drawbar attachment for your mill that you can put an extended handle on (if using or making one of the cheaper "manual" power drawbar attachments), or if you want to spend a little more on a "professional" power drawbar, they often have a "pendant" style control that will mount closer to your mill quill, and you won't have to ever reach any higher than that to change a tool.
An R8-ER40 collet holder isn't a terrible idea, but for me it'd be too slow, and since I use a drill chuck so often, I'd be using my drawbar for every other tool change anyway, not to mention probably having to change whatever I had in my ER holder in addition to that.