Cindy, I'm an FNP/GNP in solo practice. I've used AC from day one (August '06). I think my patients are probably as complex as most anyone in FP...lots of illness/problems, little that is in control. In order to know if it will work for you, you've got to download it and try it out.
I agree with Steven regarding the billing with multiple insurances. It's difficult having only a slot for primary and secondary insurances. It just is not enough. Different visits use different insurers.
I started with a billing company, and this was one of the problems in AC...not being able to designate which insurance company a particular bill goes to (at least not when you batch upload). There were other problems/nightmares as well. We are now billing ourselves via Office Ally. Thus...I cannot speak to the x-link and Medisoft. Like others, I'm anxiously awaiting the PM module.
So...no particular issues with this software that is specific to NP's...we are just like everyone else...

Barbara C. Phillips, NP
Aberdeen, WA