Abstract. Notes from testing whether to move KeibiDrop, a post-quantum encrypted peer-to-peer filesystem, from gRPC over TCP to gRPC over QUIC. The product reads remote files on demand, so the goal is to survive an IP change, keep seek latency low, stay correct, then go fast, in that order. Measured on a 12-core macOS laptop, a 4-core Linux VPS, and a real link between a laptop in Barcelona and the VPS at 72 ms round trip. Findings: on macOS the QUIC transport is syscall-bound at about 137 MB/s because the platform has no UDP segmentation offload, and the undocumented sendmsg_x batching syscall lifts it to about 700 MB/s; a teardown deadlock traced to closing a QUIC stream concurrently with a write, fixed with a stream reset; connection migration moves a live gRPC channel to a new socket, verified with packet counters; on the real WAN a single QUIC stream loses to TCP on bulk transfer by up to 16x under Wi-Fi loss, but a random seek under saturating prefetch lands in 109 ms on QUIC against about 3 seconds on TCP, a 28x difference, because the seek gets its own stream instead of queuing behind the prefetch. The design that follows: the interactive on-demand path over QUIC for seek isolation and migration, bulk on lossy links over TCP.