Same here I wouldn't want to trade in my S10 Plus for the FE. I did use my headphone jack for listening to radio stations live for when they're giving away concert tickets lol I plug it into my Bluetooth speaker. I'm going to miss not having a headphone jack on the S21. But the 10 plus has more RAM I don't think it's worth going from the 10 plus to the FE That's just me.
I'm waiting for the S21 just need to decide whether I'm going to do the plus or the ultra but I think the ultra might be too big for me. My friend went from a Note 9 will actually she kept the Note 9 on one line and opened up a new line just to get the FE so she switches back and forth. I don't know why she didn't just trade her note 9 in. She got the phone for free but has to pay 15 bucks a month on the line supposedly.