Poison Ivy or Not?

These photos were sent by JC. He thought it was a look-a-like, and I agree:

He said it grew slowly and with sucker pads as opposed to tendrils. He mentioned it was not doing any damage to the wall and in winter it dies off. He was wondering what this plant was.

I've determined it is not poison ivy because:

• The top photo shows single leaves on the vine and the fourth photo shows single leaves in the background, and poison ivy never has single leaves;
• The second photo shows the leaves close up. The middle leaflet of the 3 does not have a rachis (stem). Every poison ivy plant I've seen has a rachis on the middle leaflet which is noticeably longer than the 2 leaflets on the side;
• This plant has suckers  (tendrils with sticky disks on them, see photo 3) and poison ivy does not.

My vote is for young Boston ivy. According to http://www.britannica.com/EBchecked/topic/74906/Boston-ivy, young Boston ivy can have either single or compound leaves.

I'll be honest, though.. I've never seen Boston ivy in person, so if anyone knows for sure, please let me know!