True on the testing between the 2 drives. I was going off a chart that compared the read speeds of the different drives from the Xbox and using that as my basis. Not really accurate. I would have compared the original SD605B laser to the SD616T one but it was dead. Quit reading any media completely after sitting in storage for a few months. As for the 616T laser assembly being new, sorry but you're wrong. It came from a well used retail PC drive. The bezel looks like the machine may have been a HP and the mfg date is November 2002. I'm sure it was used quite a bit judging by the scratches all over it. Still it is in really good condition judging by how well it read the scratched game disc.
I didnt mean new as in just made - its an old drive, which isnt being made any more. I mean new as in "swapped in a good working laser unit" You even just said in your own reply that its obviously in good condition as it read the scratched disc - confirming exactly what I was just saying - that the laser is in good condition and reading media without any struggle, hence faster as less read retries.
I agree with that, it's a know fact that no Xbox DVD drive can compare to the Samsung one in term of speed and media compatibility. Sure your mod will help the drive's performance providing that the laser you put in is less worn out but I don't think Samsung went through all the trouble of creating 2 batches of laser units with different quality standards. It is more likely that the same laser are in both the 605 and the 616. At least now you have a spare laser unit in case this one dies early!