I think I was one of the first people here with the Racingline kit almost 3 years ago and, as Pudding knows from our many conversations, I have ummed and ahhed for ages about replacing them with Ohlins but baulked at the cost in relation to the value of our cars. I eventually decided against it partly because of this reason but also because I am fundamentally happy with how the car drives. It makes a sporty yet comfortable upgrade over the oem suspension, with the caveat that it is still a bit soft and at its best upto 7/10 driving.
One of the things about Racingline which few mention is how it makes the front end more pointy, possibly due to the extra rake. Adding some upgraded arbs and superpro balljoints for both extra camber and to correct the lowered roll centre have also both been very worthwhile.
Were I looking for a suspension set up between these two in price, I would have both Relentless and Sachs coilovers on my short list. At the upper extreme, the Racingline Tracksport based on AST5200 looks like pretty decent value given it comes with adjustable top mounts and drop links.