^^ Up to you .... I utilize 98% of the features, and its not only about what features, but the standard and quality of the features as well, like on a DIY I was not able to get an as good and seamless download manager as is with synology.
Nope price performance ratio is also not the way as it seems. I started off with a DIY with UNRAID for two years and then OMV and Free NAS for like 7-8 months, then tried synology. At one point of time I was using both UNRAID and Synology at the same time, and slowly and slowly I shifted completely from UNRAID to Synology. (just because of the powerhouse synology is). And though it was expensive it was far far stable, with an OS, DSM 5.0 which rocked, in all respects. Worth every penny
Again if its only as a file server and DLNA client you want to use the machine yes a DIY might be better option, but then in that case it wont even be called as a NAS, would it be? .....