they both have there pros and cons
Flashed Pros:
Play Burnt Disks
Go Online
Value more

Jtag Pros:
Runs Unsigned Code
Thats basically it

Flashed Cons:
Get Banned and can't Unban
Dvd drive can Mess up
Hassle to Keep up with Updates

Jtag Cons:
Watch Out for Bad KVs
Bad NANDs
Banned Fast
Hassle with KVs (Including KV Dealers)

Hope this Helped