As you correctly point out Pioneer also make a tray based version of the 106S called the 116S. However you may or may not be aware this does not have SPDIF on the back like it's slot based brother. This may not be a problem if you only intend to use the drive for ripping since you can still rip the digital soundtrack whether you have SPDIF or not.
I have the 116S because my personal opinion is that tray based drives are better. There has been reports of slot based drives leaving marks on the disc left from the rubber mechanism that grips it on insertion. Also I would expect the tray versions to be less susceptable to dust etc since when closed there are no open appertures.
As far as reading discs from different regions is concerned you have to consider the RPC level of the drive. Older drives were what are now known as RPC1, which means the region encoding was not locked. All new drives are now supplied as RPC2. This means the region encoding can only be changed 5 times after which it locks to the last region selected.
There is a way around this however, providing somebody has patched the firmware of your particular drive. Firmware is specific to a make and model so a generic patch is not possible. I know the Pioneer has an RPC1 firmware patch but I am not sure about the Sony, probably not yet if it's brand new.
To get a good list of different firmwares available with downloads go http://perso.club-internet.fr/farzeno/firmware/dvd/dvdfi.htm
It seems that the Pioneer and Sony models you talk about are the same specification so providing you can get a RPC1 patch for the Sony the decision is really one of asthetics, cost, and availability.
If a RPC1 patch for the Sony is not yet available then I recomend the Pioneer.
If it's Pioneer you choose, and you really must have a SPDIF then go for the "slot", otherwise I would recommend the tray based model. Mine works like a dream using software MPEG decompression. (But then I do have a 1.4Ghz Athlon
Hope this info helps... if you need any further info drop me a line.
Edited by - morrisson on 09/21/2001 06:42:25