@bHOLDher: Here are the comments from sbrown regarding the use of a hub ...
This seems to suggest that the 520gU connected to a suitable hub should perform exactly like a 500gPv2. The transaction translator inside the hub forces the use of the ehci drivers rather than the ohci drivers which are causing all of the problems.
Unfortunately that Belkin hub is quite expensive in SA and you would need to test it first. Incredible Connection at Sandton City did have one in their bargain bin two weeks ago for ~R200. They do also have others on the shelf. Personally I would retry the Koppel firmware using whatever externally powered hubs that you can borrow and wait to see whether or not anybody is able to fix the ohci drivers.
Next, I put the 4 port hub in my monitor between the dongle and the gu. It's been running for an hour w/o a problem. The free memory is stable at 1960k. It explains why the gpv2 doesn't have the problem.
Both the hub I used as well as the one in the gpv2 has a "transaction translator" that converts the 12meg transaction to a 480meg transaction. Thus, with the hub, the serial dongle is handled by the ehci, not the ohci driver. This is confirmed by the debug output when using either hub. So, the problem seems specific to the ohci part of the core.
This seems to suggest that the 520gU connected to a suitable hub should perform exactly like a 500gPv2. The transaction translator inside the hub forces the use of the ehci drivers rather than the ohci drivers which are causing all of the problems.
Unfortunately that Belkin hub is quite expensive in SA and you would need to test it first. Incredible Connection at Sandton City did have one in their bargain bin two weeks ago for ~R200. They do also have others on the shelf. Personally I would retry the Koppel firmware using whatever externally powered hubs that you can borrow and wait to see whether or not anybody is able to fix the ohci drivers.