Best Way to Carb a Stout?

You say you don't want to mess it up, but then you ask for suggestions to do something different that what apparently works for you. I would stick with your regular process.

 

There is no advantage to using anything other than dextrose. You can use DME if you want your beer to be truly all grain (assuming that it is all grain and same for the DME). You can use honey or some other sugar if you want to make it harder than it already is for high gravity yeast.

Yeast consume sugar and make alcohol and CO2. The yeast would prefer the sugar to be easy to digest, and that would be dextrose.
Cheers.

 

If you do bottle, let it age for 3-5 months before sampling. My big stouts take that long to full carb up and for the flavors to meld nicely

 

Yup, just stick with corn sugar (dextrose).

And be very patient before sampling your first bottle.

Cheers!

 

Keg it. Seriously spend the money and keg it. You will thank me one day. By the way you can bottle from the keg......already carbed!!!

 

FWIW, I'm an advocate for kegging. But OP is ready to package now, assuming he hasn't already. Selecting, acquiring, and understanding a kegging system takes some time.

 

Since its an imperial stout, I'm assuming it's pretty high abv, so the yeast in your beer might be a pretty beat up. I've had great luck with my high gravity brews with pitching 2-3g of rehydrated EC-1118 yeast with the priming sugar in the bottling bucket. It doesn't give any off flavors with long aging periods, carbonates real quick (my 11.2% chocolate stout carbed in a week and a half), and it makes a nice compact sediment layer that doesn't pour out super easily.

If this seems like too much hassle, just priming sugar will do the trick; it might just take a few months to get to the CO2 level you want.