I don't believe any of those allow you to control much more than the SNR Margin sadly. I can confirm this is the case for the Fritz!Box 7490, and the adjustment for SNRM is based on offset and is pretty limited too.
You be as well get the billion 8800axl of your list as that has been announced as end of life. They are due to release an all singing and dancing AC modem router shortly.
2 days uptime with and I have a whopping 3 crc down. I must be lucky with the line.