It helps to extent. It's typically not a huge change in growth, more so than the time it takes to get there. Once debudded, the rose will just break more buds and canes so it can reflower as that is it's sole goal. I personally, just let them flower, but that's just me. You might gain anywhere from a couple days to a few weeks in growth time if you debud the blooms though.

I know this subject has been discussed a lot, but when I search for it, it's hard to find a good thread discussing it. (can someone help me find one? I'd like to read more)

A lot of people say pinch all the buds...
and then a lot of folks pinch all the buds but one or two so that they can see the bloom.
and then some people don't pinch the buds at all.

(I wonder if anyone's done a study... though it would be hard to do it controlled as every plant is different)

As to whether this practice really is significant or not, well, the jury is still out on that. Many rosarians subscribe to the practice and say it works for the them, others, like myself, do not do it. I always have liked to see what I have rather then wait, but you do what you want. I really have no evidence or know if it makes any difference or not.

My method is very unscientific: If the plant seems very vigorous I leave all the buds. If it's on the tiny side I leave one bud to bloom so I know I've been sent the correct rose. If it has what I consider an intermediate size, I remove half the buds. I think roseman is right; no one really knows for sure, and that's why I do what makes me feel best.

Ingrid

Since these are established bushes, having been planted last fall, you'll gain little by pinching the buds. The fact they are growing well and look healthy, means the roots have become established. The main reason for pinching buds is to encourage and help root growth on newly planted plants and bands. After being in the ground for 6 months or more, you'll gain little or nothing by pinching the buds. Don't try to push Mom Nature. She'll do what she does without any help from you.
Remember, the first year they sleep, the second year they creep, and the third year they leap. This is your second year so they're still making roots and growing slowly. Next year they should do better and the following year even more so.
Patience my dear, patience. Gardeners plant for the future. If you want instant gratification, plant annuals!
My rose garden took three years to amount to anything. Now, after 7 years, it just gets better as time passes.

Thanks Karl! That's very helpful!

Thank you all for the advice! I'll just let them do their thing then. My reason for wanting them to be bigger is so that, if I plant i front of them (they are in the back of the beds) I won't miss seeing them.