General comments on club rides ratings . . .
Other than A, B, C, etc., there are two different classification systems for intensity: average pace, and pace on the flat. Some clubs use one, some the other. When they list pace, you need to inquire which it is, because it makes a huge difference.
In "pace on the flat" rides, the group will hold the given range, say 14-16 on the flat, but on the climbs you may find that they've been loafing in zone 1 and all of a sudden they're busting a nut and climbing at 2000'/hour. So that pace system can be deceptive because one doesn't know what the group is going to do.
In "average pace" rides, the group will of course go harder on the climbs than the flat, but in general will try to ride at an intensity which will most efficiently produce the posted average. However this pace system also can be a bit deceptive because one may not realize what the intensity will have to be to produce the posted average. There will be a big difference in intensity depending on the amount of climbing. For instance my group most enjoys rides with about 50' of climbing per mile. At that rate of gain, to average 16 we will have to ride at ~20 on the flat. To average 18, 22-23 on the flat. As the rate of gain per mile goes up, so will speed on the flat as well as climbing intensity for any given average.
It's actually more complicated than that because given a particular average speed, stronger climbers can go slower on the flat, and conversely, slower climbers will have to go faster on the flat to produce the same average. Hence the desire to find a compatible group with about the same climbing ability as oneself, and the need to understand the classification system being used.
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