Honestly, my answer is.. why the rush to decide?
When do you have to place her definitively... end of July?
I know the school anticipates evaluating her soon (I would not view this as a test, there is not pass/fail... it is an evaluation of her maturity and abilities for readiness, not just learned skills and facts), but you seem to already by trying to make a decision. Not just before they do their evaluation, but when your child still has 7 more months to grow and mature before the start of the Kindergarten year.
Bear in mind, that the school is likely to evaluate with expectations of advancement in certain areas between the time of the evaluation and the start of K several months later. Or not. ASK.
And you also can take this time frame into consideration. Perhaps your child is lagging in social development now, but has a great summer making new friends and becoming more socially mature. Or has a gross motor/fine motor delay that you provide therapy for over the next 6 months that bring her in line with the majority of her peers. Is Occupational Therapy on the list of things you intend to pursue for her? Is that what is recommended for a child with gross and fine motor delays? Or are you just waiting to see if she overcomes them on her own with time? Perhaps she will. Have you considered what you will do if she continues to lag in this area?
Basically, you are putting the cart before the horse a bit. Yes, I understand you are just trying to look ahead and plan. All of us have this tendency to fret and worry if we are making the right decisions about things that seem so course setting. But really, wait and see what the evaluation reflects. If you already know she is delayed in certain skills, take proactive steps to address those issues and see where that goes.
Both of my kids were summer babies. One late June, one mid-July. The mid-July child just graduated and he did fine. Would he have done even better if we kept him back a year? Maybe. Maybe not. He was ready (socially and academically and motor skills wise) and so we saw no reason to hold him back. He's not a bookworm, but that fact wouldn't be changed by waiting a year to start kindergarten. It's just his personality. I have a brother exactly the same. The daughter (late June baby) excels in every way. Except height. She's short. But, that wouldn't change by keeping her back a year either... she's never going to be very tall. It's just the genes she inherited.
In either case, if I had tried to make the final determination about starting them in JANUARY after they turned 4, it would have been too early to decide. They do a lot of growing (mentally, physically, and maturity wise) in 7 months.
I'd simply suggest you decide to wait to make a decision. Listen to the evaluation report, discuss it, ask questions. Seek therapy for motor delays (if appropriate to do that). And wait to make a final decision about it until July (or whenever you HAVE to decide by), using ALL of the available information you have at that time.
Good luck trying not to worry over it until then. But just remember that there is no right or wrong. Only what you feel is best.