Is this a good deal ?

Can you get something new through the tax-subsidised employment scheme?

Last time I looked it was possible to buy one quite regularly. Perhaps that has changed, or is only priced fro plebs like me !

I'm assuming that this comes with two sets of wheels?

If it only comes with 50mm, budget for a pair of lower profile rims. 50mm in wind is not fun.

Get a chain gauge on the chain. If the chain is extremely worn out, you can find yourself with new cassette and chain rings due to severe wear. Shiny bikes are not always well maintained bikes. Chains on 11 speed may only be good for a couple of thousand miles and some riders still don't seem to be aware of them being wearing parts.

Love my 2017 Defy. There is reasonable tyre clearance so you can get decent sized tyres, but if you want to go the mudguard route you will be limited - not possible to fit traditional guards on mine, not sure if they put a mount point at the top of  the fork by 2019.

Really, if it is a bit of a commute but really looking for an excuse to get out in the better weather, it's a happy bike. 

Hunt wheels - nothing special - I have a pair that I'm happy with, but a mate had problems with the build of his, and reckons they'd used the wrong sized spokes so they creaked and came loose. Basically foreign built wheels brought in by the lorry load. Mine new were about £600 for a gravel carbon pair. I'm not keen on deep rims due to cross wind handling and it's not like I am a pro with a choice of wheels to match weather, mine are for the Revolt to swap between winter road (Hunt carbon) and offroad (original Giant alloy). The Defy carbon wheels are better I reckon, so I am not sure what the Hunt give you - take them and sell on?

I'd have a defy in a heartbeat, never hear anything bad about them and a very popular bike near me. The wheels are probbaly overkill for what you want.. but I say if you can afford it, go for it, you'll be getting a great bike which you'll enjoy riding. 

And to be justify it further.. you might get a slightly better deal on another bike..  but if you know this is in great condition, for the sake of a hundred or maybe two hundred quid is it really worth the risk in buying an 'unknown' condition bike from the interwebs. You could end up having to replace £100 or £200 worth of bits and the hassle that comes with. 

Significantly overpriced I'd say, use the "Advanced search" option on eBay to look for sold bikes and you'll see similar (though without the spare wheels) have gone for £1200-£1500. Secondhand you can get a lot more bike for the same money or the same spec for less money. 

Might also be a bit too sporty, depending on your commute: for £2300 you could buy a brand new Scott Addict Gravel 30, for example, full carbon, Shimano GRX, ability to take wide rubber and plenty of mounts: https://www.balfesbikes.co.uk/bikes/gravel-adventure-bikes/scott-addict-...

I'd agree it's on the high side for the bike alone, but if the condition is as you say, OK. Thise additional wheels are nice and maybe worth £600 on their own with tyres, if condition is also good. So I'd say offer £1700 minus the Hunt wheels if you don't want them or something approaching the asking price if you do, and you like the bike, and it fits you, etc. 

Also as you don't know the exact mileage and/or how it's been maintained, budget £100 in the near future for new chain & cassette, a bit less if you're comfortable replacing yourself. 
 

Good luck!

Seems expensive. From what I see 2nd hand prices are falling from pandemic highs. £2300 for a 4 year old mid /upper mid range bike is a lot.

Also on a side note when buying from friends they are either offering a mate's rates too good to refuse deal or it's very hard to negotiate the price without damaging your relationship. If it's the latter best avoided.

Good luck.