Most clematis benefit from cutting back the top foliage the first year they are in the ground so cutting the foliage back on your three should not be a problem. It may be later in the season when they flower this year by your cutting back but as I said, it will do them good allowing them to get established in their new homes--not to mention that you will probably break the stems while trying to detangle them and get them woven back up into any new structure.

As to how well clematis do when transplaned, they will be like any other plant. Transplanting them will shock them a bit as they will need to get established in their new homes. They may sulk for a while or they may take off and grow like weeds. Just realize that if they do start growing rapidly after transplanting, they may be more likely to wilt since the roots may not be established enough to support all the new growth. If this happens, just trim off the wilted stems and give the plants a good drink of water. Over time they will get themselves established and be just fine.

One point, there is a big difference between transplanting a plant out of a pot where it has been sitting and transplanting a plant that has been established in the ground and putting it into a hole in a new location. Both types can cause shock, but the one where the plant is dug up and transplanted is likely to experience more transplant shock since all the roots will not be dug up and moved when the plant is moved. As a result, a dug up and moved plant may need to be cut back severely to balance the top growth with the root growth and still may sulk for a year or more before it reattains its former glory.

Wow, thanks so much for such a clear and thorough answer!

Glad to be of help.