I have a couple of thoughts. I still get a bit bothered by the perception that keeping a relationship open somehow equates to collecting lovers or maintaining a level of casualness. That is not always the case.
The guy I've started exploring a relationship with already has 4 serious partners. These are all long term relationships of 5 or more years. But he doesn't view any of his partnerships as primary. He recently bought a house with one of his partners, but that doesn't put her "first". Exploring a new connection with me is doing nothing to take away from the connections he already has. And while our connection is new and doesn't run as deep yet as his other connections, that does not make our connection casual at all.
Basically, there's a difference between being open
to new partners and actively seeking
new partners. Both have their place in open relationship structures. I'm going to trust any partners I have to be able to make those decisions while still honoring the relationship we have.
Also, with the time management issue...this is something that every relationship has to deal with, poly, mono, friendships, families and everything in between. The same guy who writes the Xeromag website wrote some nice thoughts on time management in his journal.