if you arent spending nights aboard, and are only daysailing, a boom tent is an expensive way to go (although it may be cheaper than a bimini)...
the hatch/companionway cover is a good thing when you are away from the boat.
we even use ours snapped to the sliding hatch when the top is up... as a sunshade for the cabin when the sun is behind us (our top opens up and rearward, as compared to some that open up and forward against the mast) as it hangs from the slider.
but if you are looking for a full cockpit enclosure when you are away from the boat, then that is a bit different. its kind of hard to rig a full cover so it can be used as a quick and easy boom tent, unless you have reefing gromments installed in it.
neither a boom tent or a cockpit enclosure can be used while sailing, but we have motored quite a few miles in rainy weather with our boom tent up and stayed dry.
its nice to sit out in the cockpit on a warm rainy day and not get wet or cold.... it seems to make the refreshments taste so much better
we constructed our boom tent so it would cover the entire area aft of the mast all the way to the taffrail. (it has a slot in it to fit around the topping lift) and so it would be a perfect fit when the boom was hoisted overhead on the topping lift, that gives unobstructed headroom in the cockpit when we want it the most, while we are on the hook or at the dock...