On modern hardware, are there any significant
reasons/advantages of to compile Lua using 'floats'
for numbers over Lua using 'doubles'?
Modern as in modern desktop / server hardware? No. In fact floats
may cause a slight penalty due to conversions in and out of double.
Depending on your application (and struct alignment) you _might_ get
better cache use from float.
Embedded processors, consoles, set tops, mobile phones, all of these
might be better using float.
