As for the Yamaha, I can’t comment except by saying that Yamaha is a professional, music oriented company and was one of thefirst to produce a burner for the general public (8 years ago a group of buddies shared an external 2X Yamaha because they were so expensive - approximately $1,200 CDN then).
For your other question, here goes:
You are both right.
Your friend is is right in th sense you can record and “erase” using a CD-R with DirectCD (if your burner supports it).
Of course, you are right because when “erasing” a record no actual erasure happens, even if it appears so to the user; the software simply removes the entries to the “erased” records in the TOC (which is built every time a CD is ejected in DirectCD).
As a side note, it is unfortunate that not all drives support efficient packet writing on CD-Rs: My old Plextor 1210A works flawlessly on CD-Rs using DirectCD wheras my otherwise much fater LiteON 40125S thrashes constatntly doing the same job. It’s too bad because CD-Rs are much more reliable than CD-RWs and we need all the reliability we can get when writing using packet technology, whcih is so much less reliable than regular ISO burning…