I can't give you an answer on the LG subwoofer, but I can with a Sony. It seems to work and we haven't had any problems since setting it up a couple of years ago.
What are you expecting? The sound bar and wireless subwoofer I set up in the upstairs great room sounds better than the speaker on the TV (a 46" Sony LCD unit), but it isn't great. Part of it is the room acoustics-about 16'x21' floor space with a high peaked ceiling, with peak at about 20'. I got the sound bar and wireless subwoofer because my wife didn't want me running wires to speakers, and she didn't want anything large. I compromised, knowing I was going to build out a room with much better acoustics and a better sound system. I have, and we are both happy with our choices.
The subwoofers that come with these systems don't have much power.I put mine in the corner of the room to get as much as possible. The TV is on a wall mount the swivels and extends, allowing positioning up to 90 degrees to either side, making it necessary to mount the sound bar on the TV. I couldn't find a mount for the sound bar, so I made one. It would probably sound better in a smaller room, but when turned up, dialog is more clear than with the the flatscreen's speakers.
The price on the link you provided looks pretty good. If you try it, I'd follow the instructions on the distance it should work in. I suspect you would be more likely to have problems if you put the subwoofer a longer distance from wherever the transmitter is.