RobCH
508
Well...
...I think the explanation is probably pretty simple.
Something like this : On the Gold RM011s, titanium has always been used (apart from a few LEs like the 'Ivory', etc) for the case centre to keep the weight down, and as the case back was marked RG or WG, with corresponding hallmark stamps, the centre was marked TITANIUM to avoid any confusion and to ensure the buyer was aware. Maybe even by law ?? This marking wasn't necessary of course on the Ti versions and was definitely absent (I have had the good fortune to handle quite a few)... Moving along to recent production and today, I am guessing in an effort to simplify and streamline production and assembly (maybe especially with the new RM case manufacturing facility ) it just made sense to standardise the process. And TITANIUM looks cool on the case anyway. IMHO 
That's just my two centimes
Titanium stamped.......
By: Conkers : October 13th, 2014-16:36
.......on the side of the case signifies the WG or RG models with the titanium centre case. The full titanium case is not stamped. Some of the limited editions are also stamped on the side with their limited series status for example the Dubail edition.
Yes!
By: Conkers : October 14th, 2014-17:19
I just checked and you are absolutely right regarding Paul's new Ti 11, so scratch my answer then - all the titanium ones I have seen have not had the titanium stamp on the side...........
Well...
By: RobCH : November 25th, 2014-04:46
...I think the explanation is probably pretty simple. Something like this : On the Gold RM011s, titanium has always been used (apart from a few LEs like the 'Ivory', etc) for the case centre to keep the weight down, and as the case back was marked RG or W...