A couple of observations, having been to dozens of similar types of events in the past, and having eaten pretty much everything you could serve at a cocktail gathering. There is lots of hand shaking going on, so people are constantly setting down and picking up either their drink or their plate. People will always pick up their drink, they'll abandon a plate anywhere.
I'd serve your PP sandwich/slider assembled. I agree with only 1 sandwich offering considering the occasion, but if you have to serve beef, I'd consider pulled or chopped, unless you want to slice brisket and assemble sandwiches to order to keep it moist. With a helper, you can assemble a tray of sandwiches at a time, and bring them out so they don't sit too long. Since sandwiches are your spotlight food, you may also want to tray them, and walk them around room offering them rather than letting them serve themselves out of a chafer.
if you decide to serve from a chafer, assembled sandwiches will keep people moving if they don't have to set their drink (or plate) down to assemble their sandwich. That very minute they set their drink down, someone will see their hand free and approach them to shake hands and say hello. And then they stand and chat right in front of the food, and that slows service.
Go light on your sauce. Remember, it's being held at a member's location, chances are, there will be a spilled or dropped plate. They don't want to remember you for the big sauce stain on their carpet. Same with their nice blouses/shirts/suits.
Think about when you eat a sandwich sitting down, you subconsciously lean forward so if it drips, it drips on the plate. Standing up, it drips right on said clothing. Sauce available at the end of the line for them to spoon onto their plate allows them to take some sauce if they choose. Believe it or not, if they put their own sauce on and then drip on themselves, they'll blame themselves. If your pre-sauced sandwich drips on them, they'll blame you. Offer a choice of a sweet and lightly spicy sauce. And make sure you distinguish between the two. No one like a fire breathing surprise.
Any idea how many of the attendees are women? Women are very conscious of what they snack on in the presence of potential clients, peers, competitors, or other professional women. (We men are pigs, we don't care) Sorry if it sounds sexist, but my BIL in the restaurant business agrees. Women are more likely to eat a fresh vegetables, a chicken skewer, or moink balls rather than a sandwich. Make sure you offer a fresh veggie tray, along with fruit. Some will want something very light to nibble on while they drink. Others may be going on home or out to dinner afterwards and prefer not to eat too much. It also offers something for those who don't necessarily care for smoked food.
Good luck. Hope you get some good business out of it.
Chris