Yes, the price is quite high and new drives for faster RAM2 are about to be in the market, this was one of the reasons why I took the 4551 instead.
And I don’t know if DVD+/-R wise you get the best.
But the question was if there are drives supporting cartridge discs - and here the answer is yes.
Obviously, there are big advantages for critical work:
As you don’t touch the disc. so no grassy fingers spoiling it, no dust, longer life span and less possibility of errors due to mishandling.
That comes at a price as everything in life…and when you read 100 000 writing times it is under the ideal conditions, e.g., cartridge discs.
The new fast disc will also have drawbacks, and Panasonic will be in but it is not known if they will offer cartridge, because even for the 5x discs they have a model (guess is the 9585) that only accept bare discs, besides it came to market at the same time as the 9574C. A major drawback will be that the MAX writing times will decrease to 10 000 (so just 10% of the previous) and there are some doubts about the high rotation speeds effects.