Psynymph,
I started reading this thread, because I identified with a lot of what you had to say, in the very first post. I almost chimed in with a "hey...me, too!" yesterday. I've been thinking a lot this morning about the role online fills in my life, with regards to being submissive. Being here has been awesome, to me. I count myself incredibly lucky to have met some people who I can count as friends and teachers.
With regards to your last post, I can only offer my opinions (which are, of course, only *my* opinions, and certainly should be taken with a grain of salt if you disagree), being a sub very much like the one you described. I've been in a poly relationship, offline, before I found this forum. It ended badly. I spent a lot of time away from what I truly wanted (to be a submissive) because I felt there was something wrong, if what I wanted made things go so badly. It took me a very, very long time to realise there was nothing wrong with what I wanted, only that I chose the wrong people to want it with.
That said, do I think submitting to multiple Dominants cheapens my submission? In a word, no. I'd like to hope my current Master, online, would agree. I think there is something special about him, and I hope he thinks the same of me. No matter who I play with, or talk to, he is the one that I would give it all up for, the one that I would walk away from playing with others for, if he asked it of me. But he knows what makes me happy, and is willing to allow me to submit to others (within limits, that we both discussed). Does this type of D/s relationship work for everyone? I strongly suspect not. But it works for me/us, right now. It might work differently tomorrow, or next week. If so, we'll have to re-examine it, and see what we need to change, and if we are willing to make those changes.
I can only do what works for me. You have to do what works for you. I've given up comparing myself to other subs...in my own head I'm never good enough, pretty enough, sexy enough, quick enough, etc...ad nauseum. I'm trying to learn to be happy, where I am, doing what I do, in my own skin.
Sorry if I rambled. This is only my 2 cents, anyway, and should most certainly be taken as such. If you have questions, PM away. If you disagree, please speak up...I find the discussion most fascinating.