My 2008 GX 470 still has the original air suspension system, and with 97k on it, does not seem to have any issues. I do notice that the front end is a little sloppy. It was never tight through low speed turns, etc. I am anticipating that the air suspension will fail at some point in the future, and wanted to have a plan to replace the suspension. I had thought about doing just the front struts with OEM 4runner struts, and then later doing the rear when its starts to fail. I have read a bunch of threads about folks that replace the air system with a strut system with success. Ideally would like to maintain a factory like ride, but would prefer it be a tighter, stiffer ride so it handle a little better. Would not want to do be jarring or too stiff as my wife drives it most of the time and she would like that experience. All suggestions of success or challenges from anyone who has done this are welcome.