Fuji, if the insurance company doesn't place any restrictions on you now, but you would place restrictions on yourselves and on the other pilots that use your plane, including students and low-hours renters, would your premiums go down?
I think with insurance you get what you pay for. No restrictions insurance might be more expensive than insurance with restrictions. Particularly for planes that are used in flying training and low-hour renters. Possibly even to the point where the difference is so much that it pays for a lot of check flights.