Had RS9000's and incab for several years. No failures. Used the incab all the time - very happy with it. Knocked one plastic elbow off the air line once otherwise faultless. The elbows hang a bit low for my liking but somehow I only killed the one. You can reattach the manual knob for trail repair if u kill and elbow - 5 mins work.
Now have Edelbrock extremes with remote cans. They have IAS wizardry for auto-valving and have a great ride and generate very low heat for speed work. A cosmic leap in performance from the Ranchos. And being rebuildable is cool too.
That said - the Rancho's were beaten in several spots over the years and still worked great so would get them again. Their new remote model looks pretty cool too.
5000 and 9000 are same. 5000 are just a 9000 stuck on 5 (mid) setting. If $$ is an issue just go the 5000 for the same durability without the adjustability.
cha-ching