DS3 mux recommendation

[Jay Nakamura <zeusdadog () gmail com>]

I haven't researched stand alone DS3 mux in a long time and was
wondering if anyone can recommend a DS3 Mux.  I have used Adtran
before. (Long ago)  The products back then worked fine on line level
but management interface was awful and if you threw too much SNMP at
it and the management interface locked up.

Are there anything better out there these days?

TIA,

-Jay