Hi! Love your new Manuela! With you and the other ladies looking smashing in camel, I feel so tempted to get the camel color too! I just know I won't wear it, but I think camel is the most beautiful of all the colors.
The camel color looks fabulous on you!
On size... sizing is preference, so there is no right or wrong answer.
For me, based on your photos, I would prefer the size 10 on you. Why?
The Manuela is an oversized flowing look with beautiful big flappy lapels to highlight the face. The focus is on the lapels/chest area. In your photos, I feel a larger size would give it more that look. I feel that loose flowing look is a bit lost now. I also do think your shoulders can also use the size 10.
Worn open, you can't tell and any size really works, but worn closed is where I notice it. To me, it's most important to look great when a coat is worn closed as typically one wears coats closed in cold weather. All these models wearing coats open and loose is just that.. a modelling shot. If it's 30 degrees outside or lower (which it has been for me on the US east coast... lower!), I am wrapping up!
You might be used to a tigher fit given you have the Rialto. The Rialto has sleeves that are a bit more narrow and the armpit is cut higher. This will give the illusion of a longer torso which is probably what you're used to and like.
I love the look of a long torso too, and you can create that in the Manuela but still have the loose oversized look.
It is a bit complicated to explain, so stick with me here while I try my best!

In your photo with the coat wrapped, look at both the lapels. See how the lapel on the left in the photo is looser than the one on the right? I know it was a quick mod-shot and not a glamour shot, but I need to mention the lapel to explain.
Take that same side of the coat (the lapel on the left in the photo, above the bow) and pull it in tighter, pull the bottom wrap layer past your belly button. Most people just pull that bottom wrap layer to the center of the body, where the belly button is, but it ends up looking too sloppy for me for a wrapped coat look.
However, if you pull the bottom wrap layer past the belly button to over the ribs on the opposite side, you have a base layer to create a sleek look. Then, wrap the other side over it. You will get a nice fit and the "V-neck" from the wrap will be centered and look really nice. An added plus is the "V-neck" also comes up a bit higher which is a plus for cold weather and you do not always need a scarf (I try to avoid scarves if I can). And finally, that high V against those oversized lapels just frames your face so nicely!
So... what does this do body-wise? This gives you a nice long look, yet because the cut is oversized and you still have width, you still get that loosen flowing feel above the belt. This is also why I think a size 10 would be better because notice now that you are pulling it in more, you need just a tad bit more fabric to keep it "loose" around the chest area. Manuela is not meant to be tight around the torso.
I also think the size 10 will look better with thick sweaters that have crewneck/turtleneck as there will be a lot of knit fabric up there near the chest and also thick sweater fabric on your upper back as well. Your sweater now is a low scoop neck so there is not thick knit in your V space which if there was, you may see some sweater bunching if the coat is wrapped sleek as now the chest area is too tight.
Speaking of tightness, after you have wrapped your sweater with over your clothes, cross and swing your arms back and forth. You want to be sure it is not snug or pulling around the upper back. No one just stands still wearing a coat; people move, people lift up their arms, and there's nothing worse than seeing a coat that pulls in the upper back shoulder.
I hope that made sense. That's just my thoughts, and again, it's whatever size you prefer. There is no right or wrong. I just want to share my thoughts here to help you decide.
When I got my first Manuela, I was used to very tailored coats. I work in a conservative environment and dress very tailored (e.g. suits). I was not used to the Manuela being so "loose." After a few wears, I love it and am glad I went with the looser fit that was out of my comfort zone.
Plus, the look now is very loose coats, so another reason why bigger is better than smaller.
I also want to add...
You made a perfect bow with that belt! Fabulous! The "Max Mara way" as the SAs have shown me. I love the look and have tried doing it, but it takes me forever, and I can't seem to ever get it right on the first shot. Your photo has inspired me to practice and get it right! You did it perfect with one short tail and one long tail (I give up on the short tail and loop).
One more add...
I love how you positioned the bow over the seam edge and did not place the bow on the center of your coat. My SA told me to do that as well, and I love that look. Putting the bow over the center now looks odd to me as I am so used to putting it exactly on the edge as you have done. Looks really chic on you!
If something about your size 8 feels a bit off to you now, I would suggest you order the size 10, think "loose", and see if you might like the 10. Throw on a thick crewneck sweater.
Yikes... sorry for the long post. I shall zip it now!
I hope this was helpful and congratulations again on your new coat!