I'm just sneaking in here after some lurking. I find this debate interesting too. Almost all my m/c's have been after scans showing HBs so really hit me hard as "true" m/c's.
This year we had what I would consider a CP - low positive BT after AF had already arrived (early). In my head I didn't really consider that one a pregnancy as I had already thought I wasn't when AF arrived. Probably also made it easier to deal with it emotionally. My latest loss was probably terchnically a CP as was only based on positive BT and later dropping of HCG levels followed by AF at 5.5 weeks. That one didn't hit me as hard as some previous losses but still felt like a m/c because I already had hopes and dreams built up for that potential baby. Didn't help that the IVF clinic sends all that pg info out straightaway too. Next time I'm going to ak them to wait until we are sure things are progressing in the right direction.
I think once you have a definite BFP then you are emotionally attached already. NO matter how hard you try, its impossible not to build up a whole future for the potential child in your body - even if they are only there briefly.

All my love and best wishes go out to all you lovely ladies who have been and still are going through suffering that no one should have to. We all deserve that one small wish - a healthy live baby in our arms. Something that is Sooooooo simple for the majority of the population ( a lot of whom are trying hard for it NOT to happen!).