My bottom bracket needs replacing. Question - should I keep the bike to spec and replace with the same as now used OR upgrade to the next level? Thanks.
Honestly, I would replace it with whatever was the best deal. I would not go lower, but unless you really want to tell everyone that your bike is "complete stock" I see no reason not to upgrade to a higher model. That is my two cents.
If it's already Ultegra, going up to dura-ace might not be worth the extra $$. Dura-ace tends to be lighter, but I don't know that it is as durable or performs any better. But I haven't ridden the new stuff much. Ultegra is usually considered very high performance at "reasonable" cost. 105 is good solid stuff. But honestly, as long as you're in the ballpark, it probably doesn't make much difference.