It would be a heavy old beast and introduce more blade deflection.
I currently have a 12" Bosch Glide and it's wonderfully accurate, provided you understand how a 12" blade behaves vs a 10", but man it weighs as much as a small mountain. I bought it as a one saw for every occasion, both accurate and with large cut capacity, but the thing I've subsequently come to realise is when you're approaching the point where you need the capacity of a 12" saw the requirement for perfect cut accuracy reduces dramatically.
In hindsight I'd have been better off with a £400 generic design slider and a £200 non sliding mitre saw for portability/accuracy on smaller cuts. I'd have all bases covered and greatly reduce the occasions I need to move/transport all 34kg/75lbs of the Bosch.