Not gonna get into the whole drama but:
We do have a test server, but only staff gets to use it.
We had a public test server at some point, but it did more harm than good. Once people get the nifty toys they've been wanting on the main server in a matter of minutes on the test server, they tend to PVP / Play the test server for about a week, and then quit on both main and testserver and we loose a player.
Serious. We had a testserver, everyone would get SQI's etc, and then just PVP for a few days. Then they quit. It seems to me, to have a testserver not do that, you have to withhold either content or gear, and in both cases it then can not be used to test something under normal conditions. The only way I can see a testserver working is if it's extremely focussed testing on one specific thing only with a million restrictions, but at that point the majority probably wouldn't even want to test.