The grit is exactly right - perfect.

The size of the pot should be determined by how much space you think the roots will occupy during the interval between repots (which includes soil replacement and root pruning). IOW, you can use a smaller pot if you plan to repot yearly than you can if you repot every 2-3 years. Your plant needs to be repotted when the root/soil mass remains intact when you lift the plant from its pot. Whether you repot at that time or not, depends on what you decide, but growth begins to be affected at approximately the time the roots get congested enough so the soil mass remains intact when you lift the pot.

If the gritty mix is properly made, it holds no perched water, so there is NO upper limit as far as pot size. You can grow even the smallest cuttings in an extremely large pot.

I don't usually consider the advantage of a weightier soil like the gritty mix because I usually choose container size based on the criteria I just mentioned, though there is sound logic in what you said about the weight.

Al