I've gotten around to setting up my HG658. I've not managed to completely unlock it yet as those pesky devs keeps changing the RSA key used to encrypt the config file but it is working in bridge mode with all other services either deleted or disabled.
Until I can get telnet access I can't see too much detail but I'm connected at 80/20 with slightly better SNRs of 3.3db on the DL where it was 3.0db on the HG 612. My upload has massive headroom with SNRs around 12-15db.
If you find one with an older firmware then one of the many config tools will work but mine has been updated recently - https://hg658c.wordpress.com/2015/03/17/hg658c_confi...
Overall it was well worth the £9.