Suppressors have been legal in my state for a while now... no reported increases in crime rates.
"Silencer" is a misleading term...it's not like in the movies where a secret agent shoots a bad guy in the kitchen, and the bad guy's friends in the living room don't here it.
Even with a top notch silencer, it's still going to be pretty loud.
There's a range about 20 miles from where I live that allows you to rent and use class 2 and class 3 weapons on their facilities. I've shot several pistols and rifles with silencers/suppressors and you still need ear protection for most of them. I shot a silenced Glock .45 ACP on their outdoor range using a Osprey (a $1200 device) and that thing will still make your ears ring if you shoot it without ear protection.
Another interesting thing to note is that you can't shoot it as many times with the silencer on as you could with it off...the reason for this being that the blow back of carbon, dirt and unburned powder (which would normally escape the gun) end up inside the gun so they will start to misfire and malfunction fairly quickly if you don't clean them every 20 or so shots.
While states have varying laws on silencers, regardless of their laws, if your state does allow them, there's still some federal paperwork and background checking that takes place (because I looked into it). You go through your standard FBI background check as you would to buy a pistol, and in addition to that, you need to submit a stack of paperwork to the ATF and there's a long wait before you get to take your product home.
I've considered getting one, and here's the process (federally defined regardless of whether your state allows it or not)
Obtain the ATF Form 4 (5320.4) (Application for Tax Paid Transfer and Registration of Firearm) from your dealer in duplicate. Some information should be pre-filled by your dealer, such as the dealer’s name and address, the model of the silencer you are purchasing, the overall length of the silencer, the caliber of the silencer, the serial number of the silencer, and the manufacturer’s information. Make sure the dealer signs the appropriate fields. Remember to complete all information in duplicate.
Fill out the required information on the front of the form, including your name and address. Complete the back by answering the questions and stating the reason you are acquiring the silencer. Sign and date the back of the form. Again, remember to complete all information in duplicate.
Affix a recent color passport-sized photograph of yourself on the back of each copy of the form.
Acquire a signature of the chief law enforcement officer of your county or your local sheriff.
While you are at the station obtaining the required signature, ink up your fingers and get two copies of FBI fingerprint cards (FBI Form FD-258) that you will send in with the two duplicates of Form 4.
Fill out the ATF Form 5330.20 (Certification of Compliance). This form does not have to be in duplicate.
Place both completed copies of Form 4, the two copies of FBI fingerprint cards, and the completed Certification of Compliance form in an envelope, along with a check or money order (payable to Bureau of Alcohol, Tobacco, Firearms, and Explosives) for $200 and mail to the address listed on Form 4. We advise that you use a check and not a money order so you can see when the ATF cashes your check. Approximate wait time on this step is 2-6 months.
After the ATF approves Form 4, they will put a stamp on one of the two copies you sent them and then send it to the dealer where you purchased the silencer. The dealer will then notify you that the paperwork has returned and that the silencer is ready to pick up.
...as you can see, it's not as if the state passes the law and then all of the sudden you can just walk into a sporting good store and walk out with a silencer same day. They're very very expensive devices and obtaining one is a very time consuming and expensive process.
