I have purchased a IID BT which shows on ECU info that most of my ECU's can be updated.

Has anyone done this - is there any benefit and were you charged a lot for the ECU updates ? 2015 Range Rover Sport Autobiography 4.4
2012 Range Rover Sport SDV6 HSE Luxury Black

The consensus is, don't update unless you are experiencing a problem. It's not like a Windows update on your PC. Kev

MY2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
MY2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey

Agreed, if everything’s working Then don’t update (unless it gives you more functionality). 2012 5.0 SC AB
Mods:
TPMS
Genuine LR DRLs
Remote Boot close from key fob
2016 Discovery 4 Mirrors AKA RRS2
2014 L405 Surround Camera retro fit (WIP)
2013 RRS Dual View Screen fit (Complete)
2016 LR4 RSE
2014 LR4 Homelink
2016 FFRR Electrochromatic Wing Mirror Glass

70 plate Focus ST (Current)
1942 VEP Ford GPW Jeep (Willys) (Current)
1943 Whites M16 Halftrack (Current)
16 plate Eurofighter Typhoon, 2 x Eurojet engines with 20,000lbs thrust each. 1380mph

and id agree both both of those if its not like computer firmware updates etc.

How would we know if an ECU update would give enhanced or added functions.

I know I need to update the KVM module so I can add a new key (and am expecting I will get that FOC from GAP) for example. 2015 Range Rover Sport Autobiography 4.4
2012 Range Rover Sport SDV6 HSE Luxury Black

While I understand the "if it ain't broke don't fix it" thoughts, surely there must be an improvement made with a newer firmware version, as in the manufacturer made a fix or improvement even if it did not appear to affect us?

Or why would they bother making a change and presumably applying the latest version to the current production line? 13MY Range Rover Sport Autobiography SDV6 - mine
14MY Range Rover Evoque Dynamic SD4 Black Pack - wife's
99MY Defender 90 TD5, Soft Top Conversion - my toy, and bairns favourite

JLR are having huge problems with the ICTP, with newer firmware actually making the system worse