I grew up sailing dinghies and small boats. I understand your experience of having the main sheet in your hand. Racing with the sheet helps to steer the boat and keep the boat upright in puffs.
There is a transition regarding the need to hold the main sheet on keelboats. There is a question regarding the size of the boat and how you want to sail. Cruising on a bigger boat is not a constant trim control activity. One needs to set the basic direction and trim, then let the boat go and do its thing.
This is so true when solo sailing. I find I move about the cockpit, sometimes behind the helm and other times in front, tending to trim or just stretching, taking in the view.
When racing this is not the case. Racing means a crew. We each have tasks to accomplish and stay on top of the boat.
The need to control the mainsheet from behind the helm is not necessary.
We each have our own styles of sailing. Whatever you decide, be sure you have as few turns to the sheet (each time the mainsheet lead changes direction, this is considered a "turn") as possible. Be careful making your rigging cross the path you take to move about the boat (i.e., lines crossing from the center of the boat to the side of the boat across your access to walk up the side of the boat). Limiting the turns minimizes friction. Friction makes the control of a sheet sloppy or problematic.
If I were to adopt changing the main sheet design, I'd choose a single point in front of the helm. This will move the control to a single point at the end of the boom. Far simpler and more responsive to sail trimming. Sure, It may be at your feet in the cockpit. But the main sheet block could be on a soft shackle or snap shackle and the boom plus mainsheet rig moved to the side when relaxing in the cockpit at anchor. It would be like the standard design in the original rigging image above.