Eh? No, why did you pick this key then? G tends to be quite a common key along with D but each person has a different range and sings in a different key...quite a lot of Karaoke song are now recorded in the original key....anyway the most popular and easy to sing songs normally don't have a big range in them which is why people find them easy to sing....If you want a quick test on this sing the first two notes from "Over the rainbow" which are a octave apart...not all that easy is it?....now thing that the top singers have a range of about three octaves and be impressed.
Agreed, this is not a particularly common key and I cannot see any reason why karaoke developers would transpose songs to this key deliberately. Bearing in mind also, that karaoke machine have built-in key changers anyway.