Air Suspension or coils?

[Adas]

Looks like this thread has gone quiet since January, but I am in the same position now of "do I continue to throw money against the air suspension on my 4.6is, or bite the bullet and replace with coil-overs and be problem free in the future?"

I had my rear bags replaced this week - only $550 fitted (Arnotts), so was happy with that. However, when I picked it up, they (being a good local BM Independent here in CO) said that I need to replace some sort of module which is about $570 just for the part. Ouch! The car is driving beautifully again with the new rear bags, but if I get that module replaced - which fitted would be around the $900 mark, including effort to remove all error codes etc. - then I am in to close to $1,500. And my front bags could still fail (car has done 138k miles so more than likely this will occur in the not too distant future) PLUS I have no idea when the compressor could go - potentially another $1,500 job in the future. So all up - I could end up dropping ~$4k on my suspension over the next year or 2. I would rather just spend ~$1,500 on some decent coilovers (don't want to go down the KW path or whatever they're called at $2,700 just on parts). Can anyone recommend something that is cost effective, and would ride and be of similar height to the stock air-bag suspension on the 4.6is?

Thanks!