The down side is that a lot of people unfamiliar with it will be quick to tell you that they would never use one and what an absolute failure point that it will prove to be.
I had one for about a year - it's extremely well-machined but only designed for air or nitrox to 40% - no trimix. Don't pick your rig up by the Bio Filter and it will do just fine.
I get all my gas at a dive shop that really monitors their air so I eBay'ed mine. The gas at your fill station might a little too desiccated (dry), or you may just be one of those people who are susceptible to drymouth. The Bio Filter might make all the difference in the comfort level of your diving.