Can anyone help me with this roofing/shingle problem?

I want architectural shingles to replace my roof. I live in a townhome/duplex. I own my side and the other side is privately owned. We share the roof, as in, share the peak. He and I have 3 tab shingles and I want archetectural shingles to replace my 3 tab. Some roofers say this wont work. I can see the other townhomes in my area and some have done this type shingling on their side. My roofer says different type shingles wouldnt interlock and would create leaking. Does anyone know if this will work???