OK, I never train with cycling clubs. Mostly because they don't like triathletes too much. But I accidentially got into an "A" group, 100-mile ride yesterday. Holey-moley! I thought I was going to die.
Though I didn't completely enjoy it, I can see how it would be beneficial to becoming a stronger cyclist. Training in the draft may be a tough transition to the no-draft tri, but I still think overall it pushes your limits, making you stronger.
Gory details here: http://star.trifuel.net/2009/05/03/the-absolutely-insane-century-ride/