While a transponder will make sure that your presence will be marked... that doesn't mean that everyone will be watching out for your signal. The larger ships would probably have a properly run bridge and would be aware of your position but smaller leisure vessels might not even have a radar.
Whether you have the cheapest octahedral reflector or the most expensive transponder, one major fact remains: there is no substitute for the old Mk.1 eyeball, used in conjunction with a good pair of ears.
