MongoDB Atlas Experiences

I am a current Cassandra user evaluating MongoDB Atlas. I’m curious about others’ experiences with MongoDB or MongoDB Atlas.

Has it been able to meet your write throughput needs? My applications regularly exceed 150,000 write operations per second. Has anyone had any good or bad experiences with Mongo or Atlas at that level?

I feel like basic CRUD operations are going to be great on Mongo (as long as I can meet throughput needs) but I’m wondering if I should rely on Mongo’s more advanced functionality such as aggregations and filters or if I should plan to let my app handle that. Any thoughts?

One of Cassandra’s banner features is Multi-DC replication. I’ve read mixed reviews about Atlas’ cross-region replication so this is a particular area of concern for me. Any experiences with this?

Last, does anyone have any experiences with Atlas’ VPC peering? Does it work well and is it cost-effective?