In the garage and in the loft I have 4 off 6ft long Fluorescent tube
Luminaires. (two in each location)

They are of the high frequency ballast type so there is no starter as
such and they are IP65 rated with a polycarbonate cover & clips.

Now I wish to convert to Full LED as I am sick and tired at looking at
Candles when it is cold weather outside and don't want to wait till they
warm up and reach full brightness.

So which is better and why?

Bypass the internal high frequency ballast and replace the mercury
vapour tubes with LED tubes

OR

Take the whole luminaire down and replace in its entirety with an IP65
LED Luminaire?

Regards,

Stephen.