Mike -
I had not played RCD before, so obviously I had not played the old 16th. I was actually unaware the 16th had been altered from the original until I read that on GCA in another thread. IMHO, the new 16th fits in seemlessly with the other holes, and obviously, while playing it, I couldn't detect it was not original to the layout. I think it's a great golf hole, a really tempting short par 4. At 337 yards from the back, with the right wind conditions, a player may want to have a go at the green with driver. Of course, that brings a lot of trouble into play, including those nasty bunkers. If not the driver, you could play the hole off the tee with many other clubs, even a mid-iron.
The options on the tee make it a fun golf hole, and a good birdie opportunity late in the round.
Regarding Portrush, I had my best round there, in a 3 to 4 club wind. It may have been the best driving day of my life, but I felt like there was more room off most of the tees than at RCD. I could be wrong there, since I only saw each course once. The biggest difference was at Portrush, the rough off the fairway allowed you to find the ball, and then play it. At RCD, the rough was nasty deep and if you found your ball, it was more or less a punch out. I felt like I could let it go a bit more at RP.
I thought RP may have been the fairest test of golf I experienced while in Ireland/N. Ireland.