Hi NYCcowgirl:
Lots of decent info in this thread, so I'll try to add what is missing.
You have not mentioned Black Sand Dive Retreat, but for shore dives, you cannot find better in the strait. Calm, current-free, shallow and lots to see. We don't dive on anyone else's House Reef, but most resorts dive on ours. Our menu features both Western & Asian cuisine, with "heat" added on request and dietary restrictions catered to. Cold drinks / water & ice available. Dive time 75 min. on boat day dives, 90 min. on boat night dives and unlimited time on House Reef dives (we've had guests do 2 hrs +, keeping above 10 m). Most guides in Lembeh try to fulfill their guests' wish lists, it is just whether they're good enough, or lucky enough to find what you want.
Some other points:
Lembeh has great coral / sponge gardens, which many don't appreciate. Lembeh is not just muck diving. That said, there are not masses of schooling fish and few big fish / pelagics, so Bunaken / Raja Ampat is better for that stuff. But the scenery can be stunning and wide angle is a viable option.
There are no seasons any more. Rain falls year-round. If there are floods, they do happen in Jan / Feb, but the months of highest rainfall vary year to year. Sometimes it's March / April, sometimes June / July. Downpours rarely last long. But rain doesn't affect vis as much as plankton does in the strait.
On guide to guest ration. It is not just how many guests per guide. Take into account how many people are on the boat. Many resorts have 8 - 16 divers on one boat, so a LOT of sand can get kicked up, affecting, visibility and the pictures of everyone. Pile-ups on special critters still happen as well as line-ups if there is a Rhinopias or harlequin shrimp.
Hope this helps.