^ I presume you are referring to the BDROM read rate. Anything 2X and above should suffice. So 8X is good enough and matches the current level. I have also read reports from users ripping BDs that speeds above 2X, do not necessarily result in less time. May be other factors related to the system are a constraint rather than than the read rate. So IMO 8X leaves a wide margin to be covered with the rising performance speeds of the systems.
AS far as DVD write speeds are cocnerned, one should appreciate that any combo or multifunction device is a convenience (at times translating into a necessity) with a good price-performance ratio.These necessarily bite a bit on the performance level of seperate devices.
The problem is that the optical drive manufacturers have unnecessarily hyped on the speeds to lure the users. How many times do you see the advice " do write your DVDs in 2X or even 1X speed." I have seen that even in this forum yesterday.
Unless one is burning and churning out DVDs and CDs by dozens a day, the write rates should not bother the normal user. The lower the better. A few seconds or even a few minutes more should not matter. Burning BDs can be a night time task.
The above is my personal opinion. To choose what is best for you is your prerogative. I appreciate the fact that individual mileage may vary.
Do read the user reviews of the many drives you may have in your mind on sites like amazon.com, newegg.com and other CD/DVD/BD specific forums before zeroing in on your choice. I always do.