So I was screwing around trying to figure out the best way to get the conch shells for the event, and found that running holosim seems to reap the best return. All I've been doing is taking off all my gear with a 60 (die faster), going in and dying twice, and opening the base chest. You can do it in around a minute or so, and there's a pretty damned good chance you'll get a shell or two. Haven't tried with boosted SiF, but it's way faster then MM. It's boring but it works, and you still randomly get artifacts and an occasional unique. Haven't been doing it for long, but it seems the best way for me to try and get enough to buy a crimson chest despite the fact I just don't have a ton of time to sink in during the event.
If anyone else tries this and can confirm similar results, I'd appreciate it.
Edit: You'll also fulfill the daily holosim mission each run
Edit 2: After popping some pots I've got 219 Sif and I'm finding that I'm getting 2-3 conch drops at at time happening more often. Also, depending upon what the first wave is and how fast it'll kill you, you can get two runs in a min. Got about 20 shells in a little over 20 mins.