Do I need USB jtag ?

[bakageta]

Actually takes about 45 mins to flash haxorware with a parallel jtag cable

It's been a bit since I had the parallel out, and I flashed more SB5100MoD's than haxorware, but it rarely took that long here. Disabling verification, it'd take around 12mins, and even with verification was more like 20-25. A full 2MB obviously takes a lot longer, and if you're doing a backup first you're spending even more time. Still, if you have it already, give it a go.

As for parallel not always working, that would be cable or pc issues generally. The longer the cable, the worse the odds of interference leading to bad reads/writes. Some systems also don't supply voltage or have poor voltage regulation, again causing problems. Parallel errors are essentially random, so if you're unsure of how well yours works, doing 2-3 dumps and comparing differences should show any errors and let you rebuild a good dump. You do 2 dumps, compare, and if they're identical great, if not do a third. Writing is less of an issue unless the cable is TRASH, verify should catch errors.

Bit off-topic, but I did my 360 jtag with a dodgy homemade parallel cable - a 16MB flash. I had to do 3 full dumps to get a backup, I had around 10bytes that were questionable. I think I spent 14 hours reading or writing, altogether. If you're going to possibly flash anything in the future, invest in a usbjtag. It's fast, reliable, and worth every cent in time saved. A 5101 full 2MB takes seconds, and experimenting with a new device is so much better when you can recover quickly and easily. If you seriously want to learn and test, or just like poking at your devices, you'll want one in the long run.