The NSA recommends P-7 with full incineration. Fellowes has a P-7 model, but do you really want to spend $7,000 on disposing of your credit card statements. P-5 and P-6 are acceptable for home use. P-4 is also acceptable if you aren't really trying to hide anything and just want to dispose of those credit card offers, CVS receipts and that printout you received from your vet. Disposal security sits right alongside digital security in that you have to ask yourself, how much of a target do you consider yourself to be?
I use a P-4 shredder, also from Fellowes, that cost a couple of hundred bucks, that replaced a burnt out P-2 shredder I got for $30 from Staples. I am considering going to a higher capacity P-5 if I can find one at a reasonable price on eBay, mainly for the extra shredding capacity and the hopper feeder than any additional security it provides.
How seriously do I take my disposal security in my home? Well, I'm not a target, and there are other higher value targets with less security, so why would they go after me. I shred any mail or paperwork I don't wish to keep physical copies of, but it sits in the "to be shredded" basket near the shredder for a good six months before I get around to it. There's an oppportunity there, if I were a target. And the "to be shredded" basket will contain bills from my medical insurance provider, phone bills, ISP bills, electricity bills, cheques I've deposited, grocery receipts.
Whilst I practice good op-sec within my house -- no paperwork leaves without being shredded, tightened network security, VLANs for suspicious devices, locked down networks, and 2FA where appropriate -- I'm not a target and I have very little reason to be a target, so I don't need an onerously heavy shield. I'm cautious, not paranoid.
You need to evaluate your disposal security within the context of "what is convenient" rather than "what is best."
