If you do a search on here, you will find a lot of good info.
In my case, I wanted to get the R100s and save myself a couple of hundred quid. I did a lot of direct comparison, but found the LS50s much superior.
The R100s are some of the best £600 that I've heard, but imo. the LS50s are a bit special......but there are some provisos:
- The LS50s are a reference mini monitor, so need to be in a good system......especially the amp.
- They need to be on decent heavy stands
- Personal preference always applies, and you can't assume that you will prefer the LS50s....so a good dem is a must.
When properly driven, with a good source and on decent stands, I found them more detailed, accurate and natural, with a faster more accurate bass, than the R100s. I was quite surprised by the gap.
Again, a search on here will find people that have not been happy eg. http://www.whathifi.com/forum/hi-fi/kef-ls50-disappointment.