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Update:  unfortunately, the nmrpflash was unsuccessful, both on windows and linux.  
However, I thought i would try a different PC.  well, i went back into my bag of tricks and flashed a version of factory-to-ddwrt.img and did a factory reset in the dd-wrt GUI.  i then enabled Telnet, accessed ddwrt via Telnet and erased some nvram, other configs && reboot.  dd-wrt restarted, i opened 192.168.1.1 and issued a new login and password.  then finally, i installed Newfie's first suggestion, Tftpd64 and flashed XR500-V2.2.1.10, because out of all the available official firmwares from Netgear, it was the smallest size closest to apparent Tftp 30MB flash limit.  it was 31,973KB.  so it was successful!  now I am currently running official netgear DumaOS v2.2.1.10.  I ran through initial setup to verify all was working and it is.  
My follow up question would be to ask for opinions on being that i was able to get a version other than .56 to stick, what upgrade procedures should I take to get to .114?  after i setup the dumaos initially on .10, I went into admin>backup>erase to restore defaults.  it rebooted, but I stopped there and wanted to come here and ask how I should proceed.  
Thanks again.