If you can get a benq 1650/55 those have been excellent for my Wii backups.
The Liteon 20A1P (I have 3 of them) non of them can burn Wii backups with consistency using top quality media eg taiyo yuden and verbatim example I burn a verb @4x wii starts to read it then gives up, the next one is fine, then next 3 fail, stick same image on CMC mag media and it works then go back to verb and taiyo yuden and fail ~KLON firmware in all liteons.
Switch to one of my benq and not a single failure on over 30 backups.
Trying to find a new benq 1650 will be very hard work I thought I would just mention the liteon (however the drive in my wii is brand new but no 2 wii drives are exactly the same so other users may have had no issues with their liteon 20a1p and wii backups)
It will be a question of take the plunge, use good media burnt @ 4x finding media that will burn @2x in newer writers and newer media will require a bit of luck also