As a Kashmiri with no affiliations with either groups despite having a Pashtoon uncle and a Punjabi aunty. I can't see a reason why a Pathan or Pathani/Pashtana would want to marry a Punjabi. No offence but Pashtoon people in my opinion are culturally superior aswell as being alot better good looking than Punjabi although we beat them in the latter aspect :P
No offence one of my uncles married a punjabi and everyone in my family dislikes her, mainly due to her culture. The language is just too similar to bhindian punjabi. Marrying a sindhi or punjabi is just like marrying an Indian in my opinion - if you want your children to grow up on bollywood culture and to be like an Indians, then go ahead and marry within this group.
Although they live in Kashmir despite having a punjabi heritage, i have alot of respect for the Mirpuris (yes a fair few are Koshur within this community) and they are pretty decent looking. I wouldn't mind marrying within them despite their punjabi language as most are religious and have a strong culture which is nothing similar to Indians but it would be hard, as they marry within their own kind which i respect greatly.
NOTE to all Pathans, Kashmiri and Mirpuri's stick to your own kind. Marrying within other Pakistani is making your children being immersed into a culture that is soooo similar to Indians.
Pathani/Pashtana how you can choose a good looking, polite and educated Pathan or vice versa over a Punjabi is beyond me, unless your mentally retarded.