Steve, We have replaced shocks on 3 coachs, 1991 Beaver Contessa, 2004 Beaver Marquis, and 2017 Entegra Cornerstone. Contessa had Konis from factory and Marquis by Monaco and Entegra from Entegra came with Bilsteins. At 100,000 miles we replaced Koni's on Contessa. At 38,000 miles we replaced on Marquis and at under 10,000 miles we replaced on the Entegra.
We know a few and have been told by Entegra maintenance shop personnel that numerous other Entegra owners have replaced the Bilsteins and were very happy they did. If you talk to Spartan tech experts whom makes all Entegra chassis's they will continue to talk about the 60mm Bilstein shock as the best, yet they sell the KONI as a replacement.
We are an owner like other Entegra owners and have found that the Koni gives us a much superior ride at any speed over 35 mph. At lower speeds and cornering, entering an unlevel service station or any other type side wind travel the KONI's keep the coach in a much superior handling position. Porposing is much better controlled, side sway and pitching/roll is far more controlled, wind gusts by passing semis is more stable and high cross winds on the interstate or 2 lane highways is significantly more stable that allows less driving effort.
Giving a shock a better rating by mm size is not a good comparison at all. The valving is the difference and Bilstein and Koni are totally different in their valving. The valving is where the significant ride is completely different between the two shocks. The Contessa had 6, Marquis 10 at 38,000 lbs and our Entegra Cornerstone 6 at 54,000 lbs. We were not impressed with 6 on the Entegra but upon change to the Koni's it is much better than we expected it would be. If anything it could use 2 more on the front axle but that is an engineering project.
Best place to buy the KONI's is from the web at Shockwarehouse. If you need any info on the KONI's you should contact KONI NA in Hebron KY and they are excellent to deal with on part numbers you will need for your coach. Not all dealers know the right part number for a coach.
Here is my DW views on Bilsteins/Koni's. Travel any distance and open the refrigerator. Bilsteins- catch as many items as you can before they hit the floor. KONI's - All items are still on the shelf!!!
You can call my DW Elaine at 231-218-9773 to verify that if you please. She will tell you it does not matter what the difference in the cost is as cleaning up the spilled sticky juices is impossible.