I had to think about this one for a few minutes.
If you use plugs:
You run the risk, like you said, of the perp sneaking up on you more quietly than you realize and being able to either disarm you or use his own weapon (assuming he has one) and do to you what you are planning to do to him. If he doesn't have a weapon and doesn't want to take his felony to a capitol crime, he still has the chance to blind side you.
If you don't use plugs:
While you will be able to hear things better, you subject yourself to the loud report of the firearm. It is less likely that the perp will sneak up on you, as you can (hopefully) hear his footsteps behind or in front of you.
Now let's break it down:
Yes, you are more subject to the report of the weapon in exchange for being able to hear the perp. However, you also have to realize that alot of deer hunters don't wear plugs or muffs while hunting. I'll admit that some do, but many don't. Here's what should be considered. At most, you are going to be using 6 shots out of a revolver or 12 to 15 shots out of a semi-auto. In the past (refering to people like my father), people shot without any ear protection, mainly because they didn't understand the consequences of multiple reports from their handguns. For instance, my father shot an average of 100 rounds a day, 6 days a week for about 5 years from a .44 mag. During that time, if we average it up, he shot 150,000 rounds. He is showing signs of hearing loss from that, but, with everything considered, not that bad. However, the report of the weapon inside a house does echo a bit and seems much louder than when you're out on the range.
So, it's completely up to the individual. Personally, I would not use any type of hearing protection while defending my home simply because I don't want to sacrifice hearing that person before they realize I'm there. If I do have to take a shot, I know I will get that familiar ringing in my ears, but I would rather have that than be in the hospital or, worse yet, the morgue.
Just my two cents.