Nassau County, LI - oil to gas conversion question

Have been meeting with plumbers to do my residential oil to gas conversion. I currently have a Buderus system Logano G115 with a Riello 40 F3 burner (pic attached). It is 7-8 years old and I paid a pretty penny for it.



Plumbers are providing quotes to switch me to gas (National Grid bringing it to my street in the next few months, but the time to sign the contract is next week). One plumber tells me that the cheaper option of converting the burner only is undesirable: there WILL be headaches down the line, not to mention that it is quite noisy, and he doesn't even know if he can attain a permit to do so. He strongly recommended the more expensive option of replacing my entire furnace/burner with a new system (reusing only the Buderus indirect water heater), and told me to sell my 7-year old Buderus system on Craiglist or the like.

Another plumber told me all of that is ridiculous. He sees no reason why not to simply switch out the burner to a gas one, which would save a bunch of $$. I'm looking for an impartial professional's opinion on these concerns and some advice. Additionally, if any contractors are interested in providing a quote, please call me at 631-680-4601 SOON in order to schedule it. Thank you in advance.