I have spinned up to 4 plates at a time at most. My current girlfriend was one of those plates at first, but it was clear right off that she had the potential to be more than a plate and she fulfilled and keeps fulfilling that potential up to this day that we're talking.
I understand that we guys, unless we're born tall, very handsome and/or rich, are not used to having the other gender be attracted to us like women are used to have men on their a$$es even if they are just average looking. I also understand that when a man builds up the skills as a lover and a man overall to attract more women in his life, he will indulge in this newfound "power" for some time (that's what I did). Therefore, I think what Glassguy is saying is good for beginner/novice to intermediate skills players.
Now, take this with a grain of salt or not, this is my opinion based on my own experience:
I have had one girlfriend, I have spinned plates and I have spinned plates last 1 year while having a girlfriend so I have tried and tested all three possibilities available in this "game". I can tell you that I personally find my girlfriend to be a source of peace, sexual tension release, I can sleep with this girl and get a good night's sleep (something that might sound funny, but I wasn't able to do with any other girl I've slept before), she is loyal, never pushy, feminine and other qualities that she has that made me eventually make her my girlfriend. After 1 year of being together (4-5 months as bf/gf), the sex is better (last night we had one sex session non stop for longer than 1 freaking hour, I couldn't even believe it), we hang out and have a drink or a dinner and the chemistry is better and better each time. So I am enjoying it thoroughly.
The other two women I am spinning...an older woman and a younger girl...with the older women it's mostly understood that it is not love and she doesn't get in my way, often helps financially, has found me a couple of jobs in and out of my field and is overall quite cool, we meet and bang about 3-4 times a month, go out for a dinner at a nice restaurant 2-3 times a month and she pays mostly. With the younger girl...she;s been quite cool about the whole thing, not pushy, doesn;t bother me on the phone much...but I am not feeling it much more lately.
Personally, I think taking care of 1 relationship is always better in many ways than constantly having to change women. It's like a business thing, you be much calmer knowing you're taking care of the relationship with one key member of your staff rather than changing employees all the time, never settling.
This is my point of view. Maybe so because my parents have been together for about 30 years and my grandparents for about 60 and they've had their differencies, but they always managed to pull through.
Conclusion: spinning plates might be a good thing for a beginner or a developing player, but as you go on, you might just realize that it is just *****, whether it is a 7 or a 9 or a 10, they all have a ***** and I can assure you that you will eventually come to the point where you will take a 7 that gives you peace of mind and is a feminine woman possibly wanting to have a family and be stable with you over a rotation of hotties who bring along with them all the inevitable drama and time spending and money spending and restless vibe all this way of dating gives.