Schertler only offers ebony (wood) buttons, albeit you have a choice between matte black, gold and silver for the plates. I like the Rubner heads but the plates are a couple mm longer so the spacing would be a bit tight for this guitar. I ordered the Schertler heads directly from Switzerland because they were willing to sell a 7-string set. The American dealers would only sell sets of six. The up-charge for the 7th head was $25 for a total of $150 USD shipped. Only took 3 days to make it to Honolulu!
I prefer D’Addario Dynacore EJP45TT for the lower 6 strings and buy a 10 pack of D’Addario .058 wound singles for the 7th course. I mainly use standard tuning with low B or C for the 7th course.
I play a Tiny Tenor 6 so I look taller on stage!