You just want to make sure it fits properly.
Anna, I think you were asking about the bassinette attachment though? We never had one, so I can't really comment. Only that Natty slept in our port a cot during summer downstairs for day sleeps because her room was too hot. And I used to pat her to sleep... It nearly killed my back! The bassinette attachment sounds like a good idea to me. Can't help you with the comfort thing though. Personally, I don't think babies care that much TBH. There's no way I'd sleep on a port a cot mattress, but Natty manages just fine when we go away. HTH a little.

ETA: Actually, I don't think you'd sleep them on a mattress on the bassinette as I reckon that'd make it too high and therefore they'd be more likely to fall out, KWIM? It is probably plenty comfy enough.