Mining Diff vs Block solutions

Trying to make sure I understand this right.

If I am mining to a Solo pool (ie VIABTC solo, CK solo, etc) and I set the share diff higher, my understanding is that I would provide less overall potential solutions, but that the ones I provide would be increased complexity? Basically lower amount of solutions but better chance each solution will provide a block solution? But lower diff i would submit more with less complexity and less chance that each is?

If I have 50 Ph/s and set the diff at something like d=121400000 I would submit less solutions than say d=500000, but each solution has a better chance of providing a block solution? Does this balance out statistically with the decrease of frequency vs complexity of provided solution? Am I understanding it correctly? Thanks!