For 100 yards, I think it's safe to say that unpointed bullets are fine, and possibly preferable. Generally, it's at 600+ yards where you start thinking about it.
I don't think you will be able to tease out the difference in raw accuracy potential. Pointing (aka tippping) bullets, done properly, can lower the nose drag of the bullet. How much very much depends on the original design, and can range from basically nothing to fairly significant. It's a little edge in wind resistance that may or may not be worth it to you.
Essentially, bullet noses have an optimal shape for low drag, and it's not a flat meplat. It's a curve that winds up at a point - somthing closer to a round tip than a pointy one. Tipping, which generally means smashing the meplat into a cone shape, is just a way of approximating that optimal shape. It works, but it's a fairly delicate and precise operation. There are practical dangers, however - if you overdo it, you can ruin the bullets and you might not know it. You're putting a fairly high compressive force on the unsupported jacket, which can cause it to buckle, yield, or do other bad things.
I've not shot the factory pointed bullets from Sierra (or anyone, to be honest). Some shooters will tell you that they don't trust the factory to point them properly. I don't know if that's a valid fear or not. (Like I said, I haven't shot them).
I do know that you must sort carefully by length if you do it yourself and generally be very careful about not overdoing it. I know of some very good long range shooters who do it successfully, and some others who have had bad experiences or don't feel like it's worth the risk.
EDIT: I rambled on about pointing and just now realized that the question is about plastic tipped bullets (as opposed to factory pointed hollow points). Much of the same background applies. In theory, the plastic tip makes for a more stable, more accurate bullet because the weight is more compact. Drag should be improved because the point can be made in a more optimal shape. In reality, if you look around, most competitive shooters (short and long range) go with a regular hollow point. I have ideas as to why that is, but they're speculation so I'll skip it. (Basically manufacturing tolerances). In practice, you'll likely not notice the difference, and I would have no hesitation in using standard hollow point boattail match bullets, which are the gold standard match bullet across a variety of disciplines.
