DO is slightly more reliable and uses substantially more powerful processors so on a low contention host, you can get better performance.

The catch with these are shared Avoton CPUs. So their "large" 9.99 plan is likely 4 VPS on a single 8 core Avoton would be my guess.

Not so sure ... There is a BIG gap and strategy difference between - thousands of VM on 8 or 16 Xeon cores - Scaleway technology with only few VM per node (2 to 6) with dedicated Avoton cores and dedicated memory (no oversubscribing)

Most of clients reports huge performances differences, and it's very easy to measure the difference. That's why VC1x VPS are so so good, constant performances, and for this price, it's really awesome