The ns central is one such bike.

I was curious as to what the pro's and cons are?

Can anybody enlighten me?

There are no pros except you can adjust the wheelbase. Only good if you want to run ss.

pros are it can be run single speed/ hub gear/ fixed & the wheel base/chainstay length can be adjusted

cons are it is awkward to get the wheel out from the dropouts – not awful just not xc race quick.

there are no cons either if you have adjuster screws to keep the wheel level

a pain in the arse if your not running ss or hub gears. right pain to get the wheel in and out.

transition trans am is another.

Also fire eye do these neat little things that will allow this with any frame

there are no cons either if you have adjuster screws to keep the wheel level

Its a faff removing your rear wheel to start with. And you have to faff about aligning your disc brake too

I wasn't thinking of anything with discs