You will undoubtedly get one camp that will respond that investing in a dedicated circuit may/will be a better option.
Having said that, I do not have a dedicated circuit but do own and use a Trifield EM100 line EMI monitor. To give you some basis of comparison I just took the following readings with a known (plasma TV) AC line noise maker on.
Plugging the EM100 directly into a wall outlet near the plasma TV the measured EMI noise component was 342.0mV. Then plugging it into a nearby (same room/circuit) AQ Niagra 1000 power conditioner the EMI value dropped to 206.0mV. Lastly, moving to the next room and plugging the EM100 into an IsoTek system the EMI noise component dropped to 56.0mV.
So, there’s plenty of debate regarding power conditioners in general, but some can be reasonably effective when it comes to specifically reducing the EMI level affecting your system.