My 2013 JVC RS4810 has a 46,000:1 on/off contrast ratio. The 2014 JVC upper tier models are double of that. I can only imagine what JVC's top tier, first 4K projector will display at. That is huge difference over what any Sony front projector can do and will be very noticeable in a dark environment. We are talking day and night contrast differences here. The Sony does have a lot more brightness over JVC which is nice for ambient light and 3D, but I project in a dedicated bat cave with black walls and carpet and 3D doesn't really interest me. By the way, I don't mean to imply the Sonys are not outstanding projectors; they are. I am just saying the JVCs excel in contrast. Sony and JVC projectors are way above anything else IMO and offer the most film-like images.
A German review site has measured both the JVC and the Sony projectors and they arrive at 8000 to 18000:1 for the VW1000ES and 23000 to 54000:1 for your projector that was called X55 over here:
As most will want higher brightness anything more than 30000 seems rather improbable for slightly bigger screens as with such a setting and over the majority of the lifetime of your lamp light output will be reduced to less than 450 lumens which is not much by any standard and if you strive for 14 fL it is not suited for unigain screens that go above 2.3 m.
The new models are a bit better but not by much (had the X55/RS4810 side by side with the X500/???) and even with them differences are not that apparent except for extremely dark scenes. It is true that if you feel that you need the really dark parts in a movie at JVC level than there is no other option but figuring in a variety of factors I consider the Sony superior - in a black room.
By the way: The JVC is so dark that its absolute black level will even shine in a room with white walls as it only looks that stunning when there is almost no light coming from the projector and then you also have the least issues with reflections from the walls. What clearly is not so good with the JVC models is that its already lower Ansi contrast is further reduced in bright rooms when you are watching more mixed content that is also available with most movies - Lawrence of Arabia would be a good example of this. Now how did exactly this movie come to mind?
In any case the X55/RS4810 is a great projector and would have been my choice in its price class, very nice unit and if not optimized for maximum contrast one can go up to 2.6m wide on an unigain and with higher gain screens up to 3.5m wide.