I think you will be dead on and really enjoy that brew! The Yeast strain you are using works pretty dang good for that type of beer. While the Robust porter gets even better with age, especially given your grain bill, I think (think being a loose word) that anything after 6-7 months will be refined at best. Your starting gravity is high but not outrageous for the style, so the yeast should work well. I would suggest pitching a bit more yeast than normal to allow for a quicker rest period. ( I was suggested this by a excellent brewer in the area on a stout I am crafting).
This is a very similar type of recipe that I have brewed in the past and am looking to brew again. One suggestion that worked well for me was to condition it around 60 degrees. That is a little easier for me living in MN! It might be a pain, but if you can keep the secondary in a tub of water with a towel over it to help evaporative cooling, it helps refine the conditioning and bring complex malts together in a more crisp and dry sense. Your flaked oats will be a very nice compliment to the perceived roast of this bill. I also like your hop bill, I think your target BU/GU ratio is excellent for the style. Sounds like a very enjoyable brew that offers more than one mug of enjoyment at a time. I do think some of the robust porters aim for too high of a SG with high attenuation - they get a little more harsh than intended. (spoken like someone who did this a few times - eh?)
Sounds like a great brew!!!!!!!!!!!!
The only other suggestion that I would have, and this is if head retention is a goal, is to substitute some of the Crystal 40 or Black Patent for a similar anount of CaraPils. I admit this is more of a personal preference, not at all important. I might steal your recipe!!!!!!
Good luck, I would love to hear how everything turns out.
Bottled: Imperial Hefe, Saison, Apfelwein
Kegged: ESB, Foundation Stout, Brothers English IPA, Kolsch, Bavarian Hefe
Secondary: Abbey Dubbel
Primary: Imperial Cherry Bavarian Hefe, Imperial Cherry Brussel Abbey
On Deck: World Class ESB, BKRye
"People who drink light 'beer' don't like the taste of beer; they just like to pee a lot." -- Capital Brewery, Middleton, WI