I agree that 4-5 days just simply isn't enough, particularly since you can't dive on the last day due to flying out. If you can manage it, go for at least a week.
Although I understand the recommendation to not stay in an oceanfront place if you're just going to dive, I'll have to respectfully disagree. We go to Bonaire to dive, doing 4-5 dives per day, everyday. The advantage of being able to dive right in front of your condo is worth the extra cost IMO, and I also really enjoy being able to have a beer at the end of my dive day out on my lanai, and see the ocean and watch other divers on the dock coming and going. We can decide spur of the moment to do a night or dawn dive by simply walking out of our condo and falling in the water without having to plan and drive.
We've looked at staying at GRI and the facilities and price is always very tempting, but the convenience of being ON the water and not having to always drive to dive has kept us going back to Den Laman and Bari Reef. Just my perspective.