$4400 + 27k miles - price differential between Base and S - That seems high
$15900 - I would like that for my 02S with 76K miles (No IMSB upgrade)
They are giving you $11500 for your car. For a dealer that's not bad
How bad do you want an 'S' punk?

I love my 'S'
I think with some research you could negotiate, especially if there are engine questions.
This 03 S needs a good PPI to understand what that tick is about. That's your determinator
So I say 'Maybe' if PPI is good and less cash
Remember - you are giving up 27k miles. That's 2-3 years of solid driving