Well, I’m not. Although, I’m not ready to blame Daytona sensors. I do feel that I’m closer to figuring this out and when I do I will post the results.

I'd be interested in knowing where the rotor is positioned when you do the rotor modification to use the hall effect / mercruiser distributor. I wonder if any of these other possible issues were taken into consideration. Maybe I can take a look at mine and post up a pic if anyone else is interested in knowing.
Something to keep in mind with the old school starter with nose / gear support- I had one break off once and it took out the bellhousing from getting jammed up between the flywheel. If it was just the gear that broke and not that whole support the bellhousing likely would have survived.
edit- just checked the instructions and it shows the rotor being moved 30 degrees clockwise on the trigger wheel to compensate for the hall effect dist.

BCK, My rotor modification will not be done for the purpose of using the Hall Effect distributor. I will continue to use my MSD distributor however it's looking like it will need attention in the area of phasing although Daytona Sensors doesn't mention phasing except when using a Hall Effect. After speaking to Daytona this morning and getting their input on the subject they agreed that it would be a good idea to at least check the phasing and to adjust it if needed. I've ordered the adjustable rotors (along with cap and mag pick-ups) and hope to have this complete by the end of the week.

Got ya. It just got me wondering if any of these potential phasing problems were considered when they came up with the hall effect phasing change. Since the box itself contains the timing curves with differing advance and retard capabilities why couldn't they just add a hall effect curve or switch on the box? Just thinking out loud about the capabilities of the system.

Update:

I've replaced the mag pickup, distributor cap and converted to adjustable rotors on both engines. I set the rotor at 4* advance (8* crank) and the phasing has one end of the rotor in contact with the spark plug tower at all times. The Daytona Sensor is set at 36 trigger, 35 total and 17 initial with the start retard turned off. I have the cranking pulse set at 8 which is 2 full revolutions before the system fires. Both engines seem to be starting fine. I haven't taken the boat out so I haven't really gotten it up to full operating temperature but I remain optimistic. I'll report back after I take the boat out.

Something to keep in mind , my bolts that held down the rotor (non adjustable ) got loose , threw my timing all off. The pistons did not like that at all.
Now I red locktite them and check often.
I`ts one of the reasons I got egt gauges. If anything were to happen like that again I`d see it on the temps I hope.
I also had adjustable timing chains. Used red locktite, they still came loose. Luckily only retarded the engines a few degrees.

point is anything adjustable I don`t trust.

keep an eye on those things.

P.S. I payed a bit more attention about the kickback and I think its more fuel related. If the engines are hot an I give then a little blip of the throttles before starting they have a tendency to kick back. Seems the only time I need to pump the throttles (once) is at cold start up. After that they want no more extra fuel at the start.
No fuel no kickback and they start real nice .
may not be the same situation you`re in thou.

Just saw this thread - A lot of good info here. I've dealt with the rotor phasing with my EFI motors before I switched to coil packs. I also use the timing boost with my Holley HP EFI setup.

Regarding the kickback issue, I struggled with what sounds like the same intermittent issue 2 years ago. I tinkered with a lot of the same things and found out the cause was a failing neutral safety switch in my throttles. I honestly don't know if it was the wire connectors or the switch itself... but as soon as I bypassed it, it never faltered again. I later replaced the switch and wiring to and from it that winter. My cranking timing works fine at 15 degrees with fairly high compression NA 540's.

Basically the signal from the key switch would be fine and then intermittently and very quickly pull the bendix back and then reconnect and send it right back to the flywheel, causing the kickback... I ruined 3 starters through a season while I shotgunned possible solutions at it - knowing that every next start could be the last for the starter (not a fun replacement on my side by side engine setup). For being a "minor" issue, that one really had me upset for most of a season.

Hopefully this helps you, but if not, I have to imagine someone else will have this eventually.