Berlingo XL questions

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I’m considering getting an XL / LWB and have a couple of questions, and grateful for any insight from owners:
 

1. Would I regret getting the petrol (the 110 – shame the 130 seems unavailable)?  We do below average mileage – perhaps only 6k miles p/a – but we’re a family of 5 with a rapidly-growing retriever (if it wasn’t for the dog and her crate an M would probably work fine) and this would mostly be a weekend / leisure vehicle used for holidays, camping, carrying bikes, etc.  We currently have a petrol Toyota so we’re no strangers to an underpowered car that needs to be revved hard to make progress (130hp / 160nm in a 1440kg car), but I’ve had enough of going up hills in 3rd with a line of traffic behind!  Regardless of a low annual mileage (and probably never recouping the extra financial outlay in MPG gains), I’d be minded to go for the 130 diesel if the driving experience of the petrol is going to be as badly strained as in my current car.  Any thoughts on real world driving 5/6 up?  Appreciate the 1.2 Puretech is torquier than what I’m driving currently.  I’d hope that we’d do enough longer runs to avoid DPF problems with the diesel although it’d be one less thing to worry about with the petrol.  We have a small petrol banger for most local / around town use.
   
2. I’d want to carry bikes and the occasional roof box on the roof.  The XL without roof rails seems to be a bit awkward because whilst roofbox.co.uk sell cross bars, it sounds like they’re not spaced to fit a box.  No idea if my Thule bike carriers would fit either, but they’re pretty adjustable.  Finding and fitting aftermarket rails seems to be a bit of a lottery, although guessing Citroen would fit them, at a cost.  That suggests I need one of the Flair models with factory rails, but has anyone definitely got cross bars to fit because I’ve read a few things that suggest the rails are too fat and are really decorative!  roofbox.co.uk’s vehicle search tool reckons a Thule 775 footpack will fit an XL rail (says they fit a rail with a max. diameter of 68mm), and they’ve always been accurate in my experience, but this would be a deal breaker for me so it’d be great to know whether someone else has made this work before I shell out (the XL seems to have a relatively poor towing capacity so towbar bike racks aren’t a great option).
   

 
Thanks, PbW.