I have been a customer with Delimiter since 12/01/2013, so a little under one year and six months but close enough.
To start out with, my initial setup time did take longer. I ordered on 12/1/2013 and setup was delivered EOD 12/6/2013. I ordered the X5150, standard configuration. Beyond setup time, everything had been smooth including installation over KVM (BYOL Windows). The standard gigabit port is amazing. Speedtest rates 600/600 synchronous upload and download for closest server.
There was an isolated issue in which network connectivity was degraded back in September 2014. It took around 6 hours in total to resolve and switch routing from Level3 (which was the carrier having issues). It wasn't much of a Delimiter issue as it was the carrier's issue.
Support has always been friendly and cooperative. I have not yet experienced any issues with support. They've always been quick and friendly when tickets are marked at appropriate severity levels.
I did upgrade recently to a L5520. However, during that time, they had an E3-1230 ready to go, same specs. I opted for that and haven't looked back. As of recent, they are providing SSL certificates, Blesta Interworx, and VestaCP license which is nice to have (specially SSL certificate).
Delimiter is the best budget provider with the best bang for buck. Why fix something that's not broken?