How good is a sub ?100 3d printer ?

[AutoWiz]

Having a seperate Arduino board leaves more scope for hacking

That thought is not rooted in reality. Please allow me to explain. ALL 3d printer boards ARE ramps + Arduino mega. Whether it comes on old separate boards or combined on the same PCB. They all use the same marlin firmware and all are made to the same specs. Features are the only difference. And as such coding, programming, and 'hacking' is the same across all of these identical platforms. The difference is how much space and how big of a rat's nest do you want to dedicate to your printers control solution. All of these boards will support multiple extruders and you can even add extra stepper drivers when all the sockets on the board are already in use. If you prefer to stay with what your printer came with then do that and be proud of your choice. But let's keep it real. Smoothie of course is the exception as it has a much better processor

[hutchouk]

I was assuming that by having a separate arduino board I'd be able to access the unused GPIO pins. Does the MKS Gen L board still give easy access to these pins then?

I'm actually struggling to find detailed information on any of these boards.

[AutoWiz]

I was assuming that by having a separate arduino board I'd be able to access the unused GPIO pins. Does the MKS Gen L board still give easy access to these pins then?

I'm actually struggling to find detailed information on any of these boards.

All boards have these pins. you just have to find them. MakerBase is a big name in 3d printers and finding a data sheet for these controllers is actually pretty easy. either from google or bing or the search engine of your choice. But since you said you are struggling to find info, I did this google search for you. Here is the first thing that came up in my search: http://www.robotrebels.org/index.php?topic=769.0