Fermentation creates heat, so I'd say it depends on where you want to ferment at. If you want 70 for fermenting, I'd say pitch at 65, then adjust once fermentation is going. Chances are, unless you know exactly what your temp is going to be out of experience, then the temp is going to be something other than what you really want. In other words, if you can really control temp then that's great, but if not, then it's not that easy to hit a temp and KEEP it at that temp.If your temp is 65 at pitching, then it may not be 65 at full ferment. It would probably depend on how vigorous your ferment is. If you're getting a rolling ferment with a wicked blow off, then your temp might get higher than if you're getting a slow ferment with a barely bubbling airlock. (I know, airlock doesn't represent fermentation, but it's a decent visual aid) Depending on your yeasts ceiling temp, I don't think a couple of degrees would matter as much as being in a truly HIGH temp. Either way, fluctuations aren't as good as keeping a constant temp. It will go up slightly, but if you're good at managing your temps, then you're better off. You should pitch at your fermentation temp, rather than pitching, then lowering your temp. Constant is good. Hope this helps....and hope I'm right....if not, I need to read some more.