I had a very similar setup and will give some thoughts.
First, dad has the 9.9 merc. It starts fine, but I have two major complaints: one, it is extremely heavy, and 2, it is hard to pull up for shallow water or all the way up for a landing. It will require some serious umph. Just forewarning you.
The RIB is probably made by Avon. We ha the one with teh anchor
locker forward. I would buy another one, but I think there might nbe others to consider like AB which has a great reputation too.
Listen, I do NOT work for Sailnet, but I would be shocked if you could not get a better deal via Sailnet than Westmarine. I would at least ask, if I were you.
Lastly, I will not buy any more Mercury's. Too many little issues that drive me crazy. Yamaha and Honda are my preferences. Be aware that Yamaha, Tohatsu, Nissan, and Mercury (IIRC) are all Tohatsu engines up to 9.9 or so. I think this is correct. It is 'everything else' that i smade by other manufacturers. But for some reason, my Yamaha's have been the engines I have ever had with no problems, but the merc's always seem to have little glitches that drive me crazy lately.
Just my opinions. I can exmapnd on them if necessary.
Last comment: depending on where you are cruising/going, you may need to hoist your dink at night or on some pasasges. Getting that rib up on davits was a total workout for us. You will be lifting well over 200 lbs. Get the purchase, davits, and possible winches
necessary to make it possible of you may come to hate that dink.