KPA in my experience is very personable and come from a long line of reef conservation. I am sure they can accommodate any demands you may have. For instance, they advertise many nano size items that would require far less than 60lbs.:)
I also have rock from TBS and enjoy the diversity from different regions. I do have the advantage of both being in my back yard, so to say.
I'd be interested in more details about the difference, especially between the Tampa rock (TBS, etc.) and the Keys/Miami rock (ARC and KP Aquatics).
It seems to me that all the vendors have essentially the same method ("rent" a plot of sand, put a lot of rock there and harvest it as needed). Tampa's a little bit colder, allegedly, than the Miami/the Keys and the geography and visibility conditions are different. So therefore the life is slightly different (or rather, the balance of benthic inverts is somewhat different, since I think the life in the two regions is roughly the same, just different proportions due to temperature, terrain, current, amount of runoff in the bay vice the keys which has a seagrass bed and the Everglades between the barrier reef and the mainland, etc.)
TBS as I recall keeps its rocks at around 50-60 ft (looks much deeper than KP's site). They have a lot of videos on youtube, and there are some posts about this on RC. Their live sand is taken directly from the site (something the vendors below can't do because of some regulatory issue) Honestly, their online marketing is excellent, and I like that they will ship the rocks in water to preserve as much of the life there as they can.
They also are generally using Walt Smith 2.1 rock, which is allegedly very stackable, a plus for many reefers.
Here's a trip out the live rock farm, with gopro-on-a-string footage of the farm, and a demonstration of how stable the rocks can be:
Here's video from a fairly clear day at the farm, with further explanation about the rock's stability and his belief that it attracts benthic life better than quarried rock:
ARC apparently has an area not too far off Miami beach, looks like 10-40ft from the aerial photo. I'd expect more photosynthetic hard corals (e.g. Siderastrea, etc.) and fewer NPS organism like sponges, tube corals, etc.
[video of their aquaculture site unavailable]
KP aquatics also has an area in the keys, looks like 30-45 ft.
[Post-facto ETA: I went with KP aquatics ]
