Well I've driven my 3.5 plenty and has more than enough for me, ill be virtually rebuilding the top end anyway, shoul be putting out around 160bhp by the end. The 3.5's are bullet proof too, with regular oil change's, they don't have the same probe as the bigger ones!
You may be right about power from a remapped td5, it will be comparable to my v8, and the driveability of a v8 is head and shoulders above any td land rover engine in my opinion, bags of torque and any moment, instantly, when you want it!
I'm not really interested about bhp anyway, more utter reliability and ease of workability.
Also, I've grown up around them, and between me and my old man we have several complete engines and parts, so very affordable to work with