My friend is potentially considering a Mk8 GTI CS. Difficulty is finding a car with DCC, sub 30k miles within budget. So my question is - is it necessary? From my TCR, I would say DCC is a must have, but not sure if the Mk8 CS differs and if anyone who has experienced no DCC would argue it’s not necessary. He is coming from a polo which is soft (I forgot how soft they are!) - this also means test drives aren’t an option (age and insurance…). For reference he is currently leaning towards a TTRS (which I thought the ride quality was pretty smooth but he thinks otherwise). He would ideally like Harmon Kardon also on the car if he got one - is this also necessary? How is the sound in a standard car?
Any thoughts welcome 
Speaking as a non mk8 Golf owner, IMHO whether DCC is a must have or not is subjective - we’re all individuals so in terms of ride quality what is considered acceptable or unacceptable will vary from one person to the next. Some owners actually prefer a non-DCC an equipped car to one with DCC; I might have got it wrong but I seem to remember forum member @Exonian is one such person. Other factors (particularly on a non-DCC car) might also be relevant to ride quality - e.g. wheel and tyre size and brand of tyres. DCC may make a car easier to sell come resale time, due to the perception of some potential buyers that it’s a must have. Bear in mind though that if DCC shocks need replacing they’ll be more costly to replace than non-DCC shocks, and replacement might not be covered under warranty if VW considers the reason for failure is wear and tear.
You’ve said test drives aren’t an option - I’m assuming your reference to age and insurance means your friend is considered to be a young driver from an insurance perspective. Is it just one VW dealership who has said ‘no’ to a test drive or is it now a general VW policy that they don’t permit test drives for younger drivers, even if accompanied by a salesperson? It’s a long while since I was a young driver

but I was fortunate enough to own a couple of performance hatches in my early 20’s and never had an issue with getting a test drive - even an unaccompanied test drive, although I do accept things might have changed since then.
As for Harmon Kardon and whether or not it’s necessary, some will say it is and others will be perfectly happy with the standard system. As individuals, we hear things differently, and what we listen to on a car’s audio system (e.g. the music genre, the audio source) can also have a bearing on a person’s opinion. IMHO a car isn’t the ideal environment for listening to music due to the many other noise sources that affect the listening experience - e.g. noise from wind, road / tyre, engine and passengers. I the had Dynaudio upgrade in a mk6 GTD I owned some years ago and I was underwhelmed (disappointed) by it, whereas other forum members at the time were singing its praises. In cars I’ve owned since then I’ve always just stuck with the standard system.