While reading nearly exactly 4GB using the Rockbox HSUSB Code:

[21726.612000] usb 1-5: new high speed USB device using ehci_hcd and address 27
[21726.756000] usb 1-5: configuration #1 chosen from 1 choice
[21726.760000] scsi30 : SCSI emulation for USB Mass Storage devices
[21726.760000] usb-storage: device found at 27
[21726.760000] usb-storage: waiting for device to settle before scanning
[21731.760000] usb-storage: device scan complete
[21731.764000] scsi 30:0:0:0: Direct-Access     HMS36040 4D5CF00          DN4A PQ: 0 ANSI: 4
[21731.768000] sd 30:0:0:0: [sdb] 7999487 512-byte hardware sectors (4096 MB)
[21731.772000] sd 30:0:0:0: [sdb] Write Protect is off
[21731.772000] sd 30:0:0:0: [sdb] Mode Sense: 00 00 00 00
[21731.772000] sd 30:0:0:0: [sdb] Assuming drive cache: write through
[21731.776000] sd 30:0:0:0: [sdb] 7999487 512-byte hardware sectors (4096 MB)
[21731.780000] sd 30:0:0:0: [sdb] Write Protect is off
[21731.780000] sd 30:0:0:0: [sdb] Mode Sense: 00 00 00 00
[21731.780000] sd 30:0:0:0: [sdb] Assuming drive cache: write through
[21731.780000]  sdb: sdb1 sdb2 sdb3
[21732.124000] sd 30:0:0:0: [sdb] Attached SCSI disk
[21732.124000] sd 30:0:0:0: Attached scsi generic sg1 type 0
[21733.968000] kjournald starting.  Commit interval 5 seconds
[21733.968000] EXT3-fs warning: checktime reached, running e2fsck is recommended
[21733.976000] EXT3 FS on sdb3, internal journal
[21733.976000] EXT3-fs: mounted filesystem with ordered data mode.
[23648.264000] usb 1-5: USB disconnect, address 27

No error occured :) Thanks guys.
Timing suggests an over all read performance of 2.1-2.25MB/s using 2048kbyte sequential block requests