Are you 4wd? If the wheels can spin then it can protect the diff.
I guess it is one of those things that if you spend X on the 7.5 with Bara work done that could be £x towards the setup that you know will not break but if it does work you save all the extra expense and hassle. Bara built my Weir kit Supra Diff for me as well as my Oppliger gear box and my front Quaife diff. Bara tends to tell it as it is, when he built my front diff he explained it was the best we could do under £1500 and explained where the weak links were...he also gave me the more expensive R&D option and said that would be bullet proof. I trust his word.