hey dude
I have the Prothane ones in my car. I only installed the Driver Side and Passenger Side, not the Rear Mount insert.
I posted about them slipping out here... ...a little tip that hopefully you won't have to use.
Anyway they are really easy to install and yes they do transmit some vibration to the cabin. I don't know how to convey to you how much without you sitting in my car (I'll be in Atlantic City this weekend...is that near milford?...)
But I'm a relatively picky guy when it comes to noises and vibrations and it's tolerable for me. Actually I've totally gotten used to it, it doesn't bother me at all. It's definitely not bone jarring or anything. You just might notice the rear view mirror vibrating at cold idle. It's almost a satisfying purr that suggests there's something gonig on under the hood without being obnoxious.
There are other benefits besides the OEM mount support - they also reduce wheel hop and theoretically result in more direct transmission of power to the wheels and thus faster acceleration (negligible but if you're looking for exuses

)
Anyway I recommend them. Hell they're $30 so try them and if you don't like them sell them for $15...nothing lost.