I am thinking of buying a SG-230 Smartuner.

My antenna is a 120 feet center feed dipole with 300 ohm feeder and a 4:1
balun up at 25 feet with 20 feet of 50 ohm coax to the radio.
What I need to know is - if I replace the feeder and balun with a SG-230
Smartuner what sort of improvement can I expect?

Would it benefit me to use the Smartuner on a 120 feet end fed inverted L
instead? The frequencies I mainly want to use it for are 160 - 40 meters.

Any help would be appreciated

Thanks

Andy