I recently fermented a Festbier with Diamond. Pitched at 64°, dropped to 53°, then let fermentation ride at my basement ambient temp of 63°. I reached peak temp around day 3 where the wort/beer hit 67°, then gradually fell back to 63°.
79% attenuation, which feels about right. Aroma had but a hint of sulfur, taste was clean, nice malt presence, with a bit of lemon. Conditioning now.