Just done my R (5dr Manual)/ S3 (Sportback Manual) comparison with DTD and configurator. If I were to get another R, i'd probably not change spec (Prets and Lapiz, nothing else - mainly because I really don't like the design of Cadiz, the actual size of the wheels between 18" and 19" isn't that important to me).
If I was to get the S3, i'd have to tick a few more boxes - Navarra Blue, dimming/folding wing mirrors (not much between getting the dimming and not, but still getting folding mirrors), Rear parking sensors, auto-dimming rear view mirror. Was surprised at the diminished option box, so much more as standard now - and there's about £1700 between the 2 DTD prices, but there's a footnote that the S3 price is cash price, so there's potential to take finance contribution off as the cheapest dealership doesn't include it but the next cheapest does. I'm assuming the next place may be £200 more. I'm guessing another £500 to come off the DTD price with £700 deposit contribution that is £200 cash price dearer than the cheapest.
S3 upside: The S3 would feel like a different car (rather than the same one twice), it has the better looking Nappa or Nappa/Alcantara sports seats, it has very nice dials. Go DSG and the S3 ends up being a £200 showroom tax vs DSG R £500 showroom tax (Manual S3 and Manual R also £500 showroom tax), I like the standard 18" wheels, 3 years breakdown cover included, prefer the front end of the S3 (not by much), toggle navigation (no clumsy touch screen). GFV on Audi's website is massively better than VW's on a 30k miles/3 year basis (£18162 vs £13869 - although that is old R figure as FL figures don't seem to be available right now - can't see it being any better than £16k).
S3 downside: Slightly higher insurance (no ACC sensor as standard, and even if you option it the insurance company won't take it into account), prefer side profile of the R, less standard kit, don't know if Audi have fixed the very open S3's front grille's propensity to allow the intercooler system to get peppered with stones, S3 looks a little slower on paper (they quote 0-62 as 5.3s on the S3 - haven't seen a good reason why, as it is a little lighter - slightly higher gearing than the R?).
The sensible thing to do would be keep my R for 2.5 years to get more wear out of my PSS tyres, let the leasegate stock dissipate that is filtering through right now and order another R or S3 before the next price rise is due.