I carry a M1 carbine in M1A1 configuration for a patrol carbine as a deputy sheriff. My department bought 60 surplus M1 carbines for $150 each in 2000. These appeared to have been re-imported in from Israel. Overall, they were well used but very servicable. Having some previous experiance with M1 carbines as a collector, I was assigned the task of servicing them so we could issue them for duty. This was a very enjoyable and exciting 3 month assignment.
I stripped the carbines down and completely cleaned them and replaced all the springs with new ones. The stocks that were salvageable we stripped and refinished with boiled lindseed oil, but some we restocked with new ones. We even tried out a few synthetic stocks with rails that actually worked pretty well. We also bought what seems like a ton of FMJ ammo for practice, but for duty use we carry round-nosed-soft-hollow-points.
I spent a great deal of time on the range testing every rifle. We share our range with several local police departments, many of which issue or authorize the use of black rifles. I got a lot of time shooting side by side with AR's in friendly competitions for accuracy and tactical training. Flat out the M1 carbine held it's own at anything under 150 yards. Reliablity was 100%, so for those who complain about their carbines not being reliable, you need to consider changing out those 60+ year old USGI springs.
Back to the ammo . . . I won't argue about whether the Chinese quilted jackets stopping the .30 carbine round is a myth or not, but I will tell you it WILL penetrate Level II and IIA ballistic vests. It will also defeat auto glass and auto body. The 110 grain round-nosed-soft-hollow-point is a very effective round. (Though I don't recommend the .30 carbine as a deer cartridge, I have taken 4 legal bucks with this round and they were all one stop shots at 40-60 yards.)
I have carried a M1 carbine as a patrol carbine since 2000. I have retired my rebuilt USGI carbine and started carrying a new one. A few years ago I built several M1 carbines from scratch using new Springfield, Inc., receivers, new barrels, and new/old stock USGI carbine parts. The result is basically a brand new gun.
Through experiance, stay away from 30 round magazines. Commercial magazines are a hit or miss afair. 30 round USGI magazines, though much more reliable, run $75.00+ on the collector market and aren't worth the cost. I have been using 20 round commercial magazines with very good success and that's what I use now. Of course, USGI 15 round magazines operate pretty much flawlessly.
The original question was would the M1 carbine make a good home defense weapon. My answer would be absolutely yes. Just remember, though I think the M1 carbine is pretty much over-engineered for the .30 carbine round it shoots, USGI carbines are all over 60 years old. If you are going to let your life depend on it, make sure it's in 100% operating condition.