The packages are just capped versions. So, if the checkers are saying 12Mb then it is pointless going for a 76Mb service. The 38s are common and BT have recently changed their 38 to the 52 at no extra cost.
Hardware is the same at your property and the cabinet. As for reliability - should be the same for all providers, the differences will be with the level/quality of support and any peak time congestion.
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