Agree with most of what VWL said there, just a couple of points to make!

NatEx have not taken B9R/Elites, private operators contracting to NatEx have (first batch are operating for Parks of Hamilton on NatEx subcontracted routes).  The Caetano Levante was developed by NatEx and Caetano as a joint venture and is still the prefered choice by NatEx.  They have recently ordered another significant batch (from memory 200 coaches) of Levante's but they have opted for B9R chassis this time.  The first Levante's were on B12 chassis but NatEx changed to Scania early on and this latest order marks a return to Volvo.   Subcontractors purchase the Levante through National Express as the sole agent.  Subcontractors can operate approved other vehicles but they must satisfy a very comprehensive spec including front door wheel chair access etc (why the PB is no longer a preferred body for NatEx - the BE SP wheelchair arrangement is not liked by NatEx)

I'd be all for a B9R based option (especially on I-shift, be that restricted version or not). 

The Jonckheere body would be a million miles ahead of Plaxton, Berkhoff (despite being form the same group) etc but with VDL launching a new range and question marks over the Jonckheere range in general I don't know whether they will be an option at this time.