It's a decent chassis, but there are a number of differences between the RSR spring chassis and its air suspension brethren. More than just the air bags. The RSR has hydraulic brakes vs air on the others, the towing capacity in minimal (only 4000 lbs vs 7000-10,000 lbs on the air chassis), the transmission is the Allison 1000 instead of the rugged Allison 3000MH, the engine is the modest Cummins 5.9L limited to 600 lb-ft of torque to match to the Allison 1000, to name a few things.
What I'm saying is that there are many differences as you move up the scale, say from the Vacationer Diesel to the Neptune on the RR4R chassis.
You can compare details on the Holiday Rambler site - they have an archive of previous years spec sand brochures.
Holiday Rambler RVs: Products