You have to remember that even if those members of the previous guild need/want you with them true friends will remain allied to you no matter what you choice may be. And ultimately understand you need to do what you need to do to get where ever your 15 bucks a month was meant to take you. Yes it's always hard to keep close ties cross guilds but over all its manageable.
No every guild is for everyone no matter the success or failure and any GM who really wants you to stay friends with themselves and leave the possibility for you to return will ultimately insure a steady transition for you the best they can. Because who knows you may go over there and find it wasn't what you were expecting after all no matter how hard everyone trys to make it that way. Just look out for yourself and your true friends will understand.
As always you can find me on US Ysera Horde as the GM of Prevail.