While I want to say go for the LR4, the sheer distance from a service station definitely plays a big factor. I've had mine for just under 6000 miles with no issues at all and yes, I use it off-road, mud, water and snow although nothing I would call serious.
I think it's too early to tell regarding the 2010 and 11 LR models but I suspect that the quality and reliability has somewhat jumped since Tata bought them.
I don't think you would be looking at any catastrophic failures but with that distance, even something as simple as a window or display issue now becomes a major hassle.
It would have been easier if you hadn't test driven it. I did the same thing and got hooked, All other vehicle possibilities disappeared. That being said, I would buy another one tomorrow if I could.
Good luck with a very difficult decision.
Here's a link to my last review. Hope it helps:
http://www.landroverworld.org/forums/showthread.php?t=21878
Marty