I wrote about this elsewhere in the forum, but all iHAS C drives and clones report much higher and much more errors. Also all these drives drop their reading speed often at the end of discs. I tested and verified this with LiteOn iHAS122 C, ASUS DRW-24B5ST and Plextor PX-891SA.
Dropping the read speed is consistent with them being poor DVD readers. If they only do that on poor quality discs then they may be quite useful for transfer rate testing. But if it happens on all discs it wouldn’t tell you anything about the quality of the discs.
The problem with the read speed dropping happens with iHAS C drives (and clones) and good quality discs (Verbatim, Taiyo Yuden). The same discs read fine with other drives both from LiteOn (for example iHAS B) and Samsung. The ASUS DRW-24B5ST and Plextor PX-891SA that I have are new and only used them for testing. Next time I will be careful when buying more than one drive of the same model.
The crossflash to PX-891SA was successful. But I haven’t had time to do anything more with the drive since.
As an iHAS124C it was tested with 2x MCC004 of variable/substandard quality. Compared to an iHAS124B (@PX-L890SA) it showed significantly higher PIE (46 average vs 7) and the PIF total was only slightly higher. Of particular note was the distribution pattern of the PIE. On the iHAS B scan the graph was pretty much flat, with only the slightest rise towards the end which could easily go unnoticed. But the iHAS C scan formed an obvious ‘U’ curve, with very high levels towards the start and end of the disc. Given my past experience with this particular pack of MCC004, I suspect this was due to the quality of the disc rather than just the reading characteristics of the drive. And by being a less good reader, the iHAS C was able to highlight an issue with the disc which the iHAS B did not. With the second disc the iHAS C again had higher PIE levels than the iHAS B, but the difference was smaller and the distribution pattern was similar.
A brief test after crossflashing the iHAS C to PX-891SA confirmed that, as expected, its DVD scanning characteristics had not changed. (In my experience scanning performance is determined by the hardware rather than the firmware, although firmware may disable or change what features are available.)
I have not experienced slowdown with any discs.