Has the mechanic who gave you advance about using the Giant ever done any long-distance rides?
It seems to me that the Rawland is a great option, and especially so if it was the bike you were riding when the first attempt at 200km failed. Make it a winner along with you on this ride.
The seating difference between the two bikes shown is quite dramatic; much lower handlebar positioning on the Giant. If necessary, you can achieve the same positioning on the Rawland if needed by taking the drops, and if things get difficult or tiresome, you can sit back up and take the top of its bars.
I have to say that having seen the finishers of a recent randos series round the island where I live, while there were CF bikes and similar one to the Giant there, their fitting was also along the lines of having handlebars up at or very near seat level.
All the bikes I have used for long distance (randos, 24H races, and fleches, and even touring) have had similar arrangements to those I have suggested here.