For me it's a coin toss. If I have the cooker space (and the venue allows it, if traveling), I like to cook as much of the meats as possible onsite and have it fresh out of the smoker. The down-side, as mentioned in a round-about way, is you'll have less time to spend with guests and family when tending cookers.
This past weekend I traveled out of state for a smaller 2-1/2 day family gathering. I hauled my gear, cookers, supplies and much of the food I contributed (as well as local purchases), including a large batch of pasta salad (prepped the evening before). For certain dishes, I precooked my bacon so I wouldn't have to spend the time doing that on site. Others attending prepared some extra sides and deserts...it all worked out beautifully and there were happy bellies and smiling faces with every meal.
The main considerations with larger quantities is cooker space and time. You have to manage your capacities and time-frame to what works for your situation. If precooking is the only way that you can comfortably bring it to the table, then, you need to stick with what you know will work. While I'm not a huge fan of reheated ribs (I'm damned fussy), I have done it and they work fine. Go with your gut.
Also, it's easy to cook entirely too much meats...been there, done that, all the time. If you have 2-3 sides there are always excess meats, in my past experience. One slab of BBs will feed 3-4, spares 4-5. 8lb precooked weight of butt feeds 15-18. You may be able to reduce your quantities based on these numbers...maybe not...not knowing your expected head-count, that's up to you.
Good luck, good smoke, and enjoy the experience while you learn along the way...it's all good.
Eric