Will a hero’s stats be affected if I ascend him to the final level but do not level him completely (for e.g. - a 5 
to 4.1 & leave it there, not taking him to 4.80) & level the costumed version completely (in above e.g., the 5 costume is @ 4.80)?
So, the scenario is that the regular version 8s @ 4.1 & the costume is @ 4.80
Will this make a difference in the stats?
I think the above should work if I intend to use the costume only.
Please share your thoughts
Unfortunately embleming a 4* is important, but yes, I have a whole bunch of 3* and a 4* (Kashhrek) who are at their last ascension level 1 (original) and their costumes are maxed, and I use them in costume version only. And the costume version has costume bonus and stats at maximum.
Since costumes are maxed much easier than the original and faster, this helps you build a strong force ASAP and have the originals leveled up and emblemed later at your leisure.
Edit: You cannot limit break a costume that way though since you will have to max the hero and then limit break him. But you can (after LB both the hero and the costume) level up only the costume with the same effect.
Edit: Hopefully you noticed that, but giving feeders of the same color to a costume gives 50% bonus xp, whereas if you feed on color feeders to the original this only gives 20%. So when powerleveling both the hero and the costume, it’s the best idea to give on-color feeders primarily to the costume and off-color to the original.
Not only does it work but often recommended. As mentioned above it does affect embleming.
Thank you for responding. The embleming & the LB part is a deal breaker though. 
Thank you for the detailed guidance, Saros. Much appreciated!
