In my opinion, yes it would be fruitless. It is NEVER a good idea to trade in a phone to Verizon as they will ALWAYS give you less than what the phone is actually worth.
Verizon is offering you UP TO $300 for any phone you trade in, so let's say they give you the full amount of $300 and that is if there is NO physical damage such as scratches, cracks, etc...
Another option would be to sell your device on your own at a site such as swappa.com. The S7 Edge has recently sold on Swappa.com for between $439 and $575. Even if you only get the low end of $439, you are still getting $139 MORE than the maximum Verizon is willing to give you. That would go a long way towards the purchase price of the Note 7.
I would NEVER consider trading my phone in to Verizon in exchange for credit towards a new device.