All this talk of ditching should be irrelevant. The industry has invested a huge amount of time and money on twin engine operations so that we should never have to ditch following an engine malfunction (OK PC2e is worthy of another thread). We now are in the situation where the next focus of attention should be never having to ditch following a transmission failure.
Of course the mechanical bits of the MRGB are designed such that the chances of failure are so small, they should never fail in the life of the gearbox. Great - the way it should be. Sikorsky tried this approach for the lube system on the S92. Maybe on the basis of the Blackhawk family, Sikorsky had a rightful claim to the "extremely remote chance of failure". Clearly this wasn't the case with the titanium bolts on the oil filter. But perhaps it is true now they have changed the bolts?
It strikes me that the inclusion of the 30 mins dry run capability is a cop out clause because manufacturers couldn't meet/proove the extremely remote chance of failure requirement. If the lube system was as reliable as the rest of the gearbox, we wouldn't need any dry run ability.
I have no idea if viable technology is available to make MGB lube systems as reliable as the rest of the gearbox. If it is, then FAR 29 should be ammended to remove the 30 mins clause, forcing manufacturers to make their lube systems reliable enough. If not, then instead of 30 mins, the regulations should simply require that following a failure (partial or total) of the MGB lube system, the aircraft should be able to return to a safe place to land. In other words, the dry run capability should be related to the range of the aircraft.
Of course this will probably mean some form of emergency lube system, like that on the S61 (by the way 2 hours at Vy!!!) or a glycol cooling system a la 225. Of course the reliability of the emergency system must also be regulated and we as pilots must be able to test the system is working prior to taking it flying. After all we need to know we really do have the ability the book claims.