i'm curious, too as i have some type 2's that i never seem to trim when i should hand they bloom well for me, if high up. Will it hurt them to trim after they're done? Or should i just wait til next year?

The typical pruning rules for type II clematis are that they are not pruned back each year and when they are pruned back, it is to remove deadwood and to contain the size of the plant. That being said, clematis of all pruning types benefit from being treated as type III clematis (ie cut back to within several inches of the ground) the first and second years in the ground. This helps the plant get its root system established and causes dormant buds to break on the crown, resulting in more vines coming up out of the ground.

That being said, I personally treat my type IIs as type III each and every year. Sometimes they are cut back in the winter when I cut back my type IIIs and other times I wait until midsummer when the vines tend to get brown and crunchy regardless of how much water I give them over the course of the summer. When I trim in midsummer, I typically cut the plants back by half, fertilize them with a slow release fertilizer, and keep them watered. They reward me with another big flush of blooms in the early fall. Another good reason to treat your type IIs as IIIs is that as the type IIs mature, the lower vines tend to get woody, you get less or no leaf growth on them, and you end up with a clematis with what is referred to as 'naked legs.' Treating them as type IIs, either yearly or in alternating years, helps to prevent this condition. Consider the pruning rules for all classes of clematis as basic rules that are not written in stone, but just general guidelines.

Here is a picture of Proteus and Piilu that were cut back to within several inches of the ground this past winter and they are both back up to over 5 feet tall and still blooming like mad in my garden. People in colder zones may not be able to get by with treating type IIs as type IIIs since the type IIs bloom on older wood and in the colder zones, the vines may not have enough time to mature to produce the buds for flower production. Those of us in most parts of NC don't have to worry with this. Experimentation with your pruning of any type of clematis in your own garden will let you know what you can get away with and what you can't. The only downside to treating type IIs as type IIIs that I can think of is that some of the double flowering type IIs require both old wood and a winter chill to produce the double flowers.

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Closeup of double blooms on Proteus.
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Closer up view of Piilu.
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Thanks for the explanation! maybe once the bloom is done, i'll get brave and cut mine back by half.