video5 - encoding question

[lou1z]

i'm not really a video guru and just play them as and when.
i've noticed that video5 encodes my mkv's to m4v's and the size is considerably smaller.
how does this compare to the original?
does it hold up on a 46 inch led tv?
should i delete the original mkv to save space?

[cpg]

it's ok, more than OK for me!

probably not so much if you are a purist