Yes, I can help you.
I have the exact same issue, but on 2-7.
Extract that molar as soon as possible.
I left my 2-7 a bit more, and then there was some transmission between the maxillary sinus and the molar which was affected with periodontitis plaque and bacteria.
I suffered a very painful odontogenic sinusitis which required the extract of the molar (It was already coming out by itself), and then the same oral surgeon punctured the sinus to do an anthral wash, by removing the infected contents from the sinus and cleaning it up with antibiotics.
Healing was very quick, but the procedure left me cheek kind of stitched to the gum a bit more than natural, and it sometimes is painful and even the ear is affecfted sometimes (Small spasms in the muscles related).
It will be possible that during extraction a small bit of the sinus floor will come with the teeth, in my case they were going to drill through after all, so it wasn't an issue, it was part of the procedure.
To have an implant there you will need a ridge augmentation and a sinus lift. I'm still thinking if getting one, my periodontist and the surgeon doesn't suggest doing so, instead going for a bridge due to all the issues concerning a possible sinusitis appearing and infecting the bone grafts.
I've zero interest in an implant because:
-my dentist assures me there's virtually no chewing contact between it and the corresponding lower molar (so, an implant would at best merely be shielding my gum from incidental food contact)
-my bones are old enough that any drifting created by a nearby empty socket will be very minimal and should have zero impact on my adjacent tooth (1-6)
I see my first step as a preliminary consultation with the oral surgeon:
- to see if he can manage a more penetrating x-ray (to get a better sense of the not visible 3rd root's penetration of the sinus floor);
- to discuss his comfort level with the procedure / similar earlier experiences and what he sees as my reasonable expectations along with his worse case scenario;
- while locally dental costs are at my own expense (& I lack dental insurance), I'd also like to get a sense of just how far that goes if there's major complications. eg. Is that all on me, or does (as is usual for my area) any medical expense get paid for by my country's province? I know for sure if I were hospitalized, I'd be fully covered but there's a lot that can be done that's costly outside of a hospital setting.
If I thought the costs could possibly be massive, I'd consider signing up for Blue Cross, and stalling for a couple of years until pretty full dental/surgical procedures were covered.
I've lived with this tooth problem for a decade, I'm reasonably sure I could coax it along for another couple of years [continuing with diligent hygiene (warm saltwater & a Water Pik), and being more rigourous with twice daily perio mouth rinse containing chlorhexidine squirted into the gum area). My gum rinse went 'bad', and I'd delayed replacing it so hadn't been doing rinses for a few weeks prior to my Wednesday checkup/x-ray (my dentist measured my gum pocket as 9 mm, the deepest it's ever been, earlier it fluctuated between 7 mm, much of the time, and 5 mm).
I had my lower right molar (4-7 extracted) several years ago as I was scared at need a course of antibiotic to settle down its deep gum pocket related infection (it had had a root canal, my 1-7 a live root), and the extraction went very smoothly and I was on the verge of proceeding given just that experience as a comparable. But I can see where the sinus floor for my 1-7 could lead to serious complications.
I do get your point about the sinus floor proximity also meaning an infection from delay has greater, perhaps far greater problem potential.