The trip to the Blue Hole shouldn't take 2.5 hours each way. 2 hours is more like it. Take Amigo's Pro48. Comfortable ride, good clean head.
I too was originally discouraged from going to the Blue Hole and so on my first trip down, I didn't go. On my second trip down, I went anyway and am ever so glad I did. I've been back in the Hole at least 5 times and come out of the water every time saying "Again, again, I want to do it again". If you see the sharks, you'll never wonder whether you should have done it or not.
True, it is a dark hole, no pretty coral, hardly any fish. But once at depth, you will be swimming amongst the stalactites of the pre-iceage cave. You will be diving where Jacque Cousteau has gone before you. I have found small chambers in the walls and they have little fish in them, so take your flashlight. I've had a shark circle around and come up to swim ever so slowly immediately below me. There are as many people that love to dive the Blue Hole as there are that say, been there done that. Some people get it and some people don't. Myself, I've rarely met those that didn't think it was pretty great.
The two followup dives are outstanding, the lunch is served up on an idyllic island and you head home being served Belikens and panty-rippers. All in all, one helluva way to spend the day.
Maybe if it is rainy or particularly cloudy, it's not that fabulous, but I've only ever encountered those conditions on one trip out there. I don't recommend this dive to those that are not experienced divers. If you decide to go, get a bunch of local diving under your belt first and then head out.
A fish and a bird can fall in love, but where will they build their nest?