Your are correct. Downgrade with hardware only right now. Also, depending on what the sku model is, there might not be anyway to downgrade at all atm. Check the sku first before buying anything. Another thing, check around online for a possible local or nearby downgrader.
Having the hardware to do a downgrade is always a great idea (imo), It also helps just in case something gets messed up by accident down the line. But, yea, its only hardware atm. As I said check the SKU also as newer consoles (factory/out of the box w/ 3.56+fw) currently CANNOT be downgraded at all.