I agree with much of what PPs are saying, having recently sold our long term home. I certainly would be sceptical about anything the EA said.
The housing market can be very volatile, going on past sale prices is a good idea, but selling prices can go down, as well as up.
We kept a price in our heads that was the lowest we would accept and didn’t disclose it to anyone. Psychologically it helped deal with the ridiculous offers and pushy EA.
Another factor to consider is where/ what your next house is. You could lose or pay more your next property, by waiting for the full priced offer. It can be a balance, in a rising market you could soon make up the financial the difference in your new property.
It’s a tricky, stressful time made worse if you haven’t moved in a while, everything seems to have changed, especially the paperwork involved.
Good luck, I hope it does go smoothly.