I also kept 2 of 5 plastic ones I bought. Mine haven't given any problems. I think they'll last the 9 or so months before their batteries don't hold a charge as well. I'll use the internals minus the battery for a box mod or something after that.
Discount vapers hooked me up a good deal on the return. I didn't get to keep mine though, which would have been stealing anyway if I kept using them. They refunded my card instead of store credit because I was returning 5 grooves, but 5 grooves turned into 4 which turned into 3 which still got me refunded instead of credited like they were offering (Don't need anything they have in stock).
I probably could have called my credit card company and gotten refunded instead of credited either way, but DV has good customer service, and good prices.
DV's recall notice says somethign like [you will only get return shipping of $5 for a Groove, because that's how much we are being reinbursed for]. I sent three in a $5.05 package and got $5 back. DV might have shown three returns to Smok and gotten $15 back. some/all of which I feel entitled to, but DV didn't argue with me to get CC refunded instead of store credit, so I didn't open a can of worms about that.
If the vendor the OP says is selling metal ones, definitely definitely report them - they easily go thermal if just dropped/bumped.
Smok said the plastic (and metal plus the issue with the screws puncturing the battery if bumped/dropped) have battery protection problems hence the plastic recall. I searched and found no reports of any problems with the probably thousands of Grooves out there people have used for many months before the recall. Maybe Smok wanted to play it safe, or maybe the problem is triggered by a very rare scenario like charging the groove with a very high volt USB port (5 volts is the highest I beleive) that no one reported a problem with.
Also, for the record, I drop tested three grooves before returning them - they're very strong. I eventually had to smash them to get them to crack.