The closest I would get to an SDR would be a 7300. I've not heard one on AM as all my locals who run them do so strictly on SSB. And even though the locals who own those 7300 are ticket holders they spend most if not all their time on 38 LSB.
Couple guys around here use the 7300 on 11 meter AM, and I think they sound weird. On the other hand, I know a guy that has a 718, and it sounds good on 11 meter AM. Was really surprised the 718 sounded that good.