...-I would love to get some local insight on the decision.
This is just my humble opinion, with backup links.
* Top side you have zero problems. 9/3 and on, it's the typical Florida weather with a short shower every other day in the late afternoon well after your morning dives.
* Even your boat rides out to the best sights are going to be really good. Look at windfinder's wave height but also duration (swell) and it's better than normal for September.
Wind, waves & weather forecast Molasses Reef - Windfinder
* So rain is nothing, waves are nothing, swell is nothing. That leaves Viz and Viz alone to consider. Outside of the 3 just mentioned, the 3 most prominent other effects to viz are the gulf viz and the current that carries it and if the army corp is totally dumping Lk Okeechobee thru gate S79. S79 dumping would need to be all 8 open gates for 2 weeks to dump enough crud to effect Largo and even then a strong gulf stream could clean it out. Below is a link to the "LIVE" gate openings and you can see they are still closed tight or pulsing (opening/closing slightly) to clean out sediment.
Lastly would be a gulf swell, but even this storm is not likely to produce any "tidal surge" (primary swell) because it just doesn't have the strength. The wave3 models also say that and below is a link also.
In short, I'd say you might find some of the most perfect conditions for diving next weekend, no way would I cancel. I'm scheduled to dive further up that coast on 9/4 and I was kinda hoping we had BIGGER waves to move more of the lobster into the shallows, but that's just me. Have a great Labor Day weekend vacation !
Links Okeechobee gate openings, Look for S79 which is eight huge 12ft wide/12ft high gates in Fort Myers on the FL west coast
http://www.sfwmd.gov/portal/pls/portal/realtime.pkg_rr.proc_rr?p_op=COASTAL
Wave III Click on the primary swell to see it's zero or nothing next week
NWW3 Product Viewer