Housecue,
To answer the original question you asked, yes it will be the same as if you originally purchased a 19 oz cue. As far as changing the balance point, I don't see that moving by more than 1/2" or so.
Food for thought : Let's say a builder, be it custom or production, builds 100 cues using the same mtrls. and specs on each cue. Chances are that very few of those cues will be of exact wght. as another in that group. It's just the nature of the beast. Wood is funny that way. Just as the overall wghts. of these cues will vary, so will the balance points.
Your primary concern is the wght. of the cue and the balance point should be considered secondary at best. If a precise balance point is a concern for you, there are ways to adjust that 'slightly' as well.
Wght. bolts are used to sell the same style of cue to a wider range of buyers, particularly when each of those buyers could potentially want a different wght. cue. So, if you want a 1 oz. lighter cue, change the wght. bolt. That's what it's there for.
I hope this gives you a better understanding.