Circling back to the project at hand, I would say insist on the lighting systems you want. If Wenger/Strand won’t give it to you, ETC or your chosen vendor will produce drawings for you. At the end of the day, it's your money and you should not be beholden to the manufacturer's rep who happened to land a key role in the project team.
I would also make sure that their relationship to the project doesn't forfeit you ability to solicit a competitive bid. If everything bids out Clancy/Wenger/Strand/etc no substitutions, then none of those vendors or the installers of those systems have a motive to give you favorable pricing. Not to say anyone will beat you up on pricing out of malice, but if they aren't afraid of losing the project to someone else and price a little higher, even an extra 1% margin on $600,000 of theater equipment scope is an extra $60,000. If they're subbed to electrical you can tack another 15% markup on that and then another 15% markup to the CM. Now that $60k increase could cost you $80k -- whether you pay an extra $80k for your project or to avoid blowing the budget they have to carve $80k of features out.
I would also make sure that their relationship to the project doesn't forfeit you ability to solicit a competitive bid. If everything bids out Clancy/Wenger/Strand/etc no substitutions, then none of those vendors or the installers of those systems have a motive to give you favorable pricing. Not to say anyone will beat you up on pricing out of malice, but if they aren't afraid of losing the project to someone else and price a little higher, even an extra 1% margin on $600,000 of theater equipment scope is an extra $60,000. If they're subbed to electrical you can tack another 15% markup on that and then another 15% markup to the CM. Now that $60k increase could cost you $80k -- whether you pay an extra $80k for your project or to avoid blowing the budget they have to carve $80k of features out.