Using a low Curb bit in Reining?

I have a 6yr old APHA mare that is broke broke broke and this Spring I am starting her for Reining. She has an amazing natural stop, good turns, quick back ups, and a wonderful topline etc. She seems to be a natural and I think she will do wonderful.

I have had her in a copper snaffle tom-thumb for the last 3 years, and she has finally figured out how to work around it. She began pushing right through, pulling the reins into her mouth with her lower lip and yanking the rein away from me, etc so I decided to try something different. I just recently put her in a curb bit (very low curb) and she took to it AMAZING. She is much more responsive, and is that much closer to being finished.

I wanted to get a few opinions though...since I am starting her training in Reining, what is a suggested bit to use? She has a very soft mouth and I have a very light hand, so the curb may be a bit harsh but it is working great for both of us since it is being worked with correctly. I've seen professionals use all different bits from the normal tom-thumb to very fancy high curb bits. I was just wondering what everyday people/trainers think about what would be a good bit to use, and if it is alright to train into reining with the bit I have on her now since she is doing so well. Anything helps, thank you so much!

Here is a picture of the bit I have her in now:
Roller Curb Bit


And here are a few pics of bits that I have seen others using:

First there is no reining trainer or rider who will use a tom thumb. They are not even close to what you want.

Of the bits you posted the 2 and 4th are more in the ball park of what you will see with most reiners. I do not have just one bit I use as all mine will take just about any bit and work the same as the bit is not what makes a reiner. I like the higher port buts as you have to move your hand less to get what you do need from the horse. Also most reiners like the shanks to swivel. Again helps with some of the cuing of the horse.

That is what I have heard with the high ports. She is just so light and new already to the low curb, I don't want to push her especially since I wouldn't know what I am doing with a bit like that. The roller curb I have her in now, is that at least acceptable to get her started in and perhaps by the end of the summer start some lower level competing in? Would it follow regulation or are there certain bits that are necissary?

There is no one bit that is "necessary". That bit will work as a step up but the thing is that you need to work on not needing a bit. Also keep changing the bits around so the horse does not figure out a bit.

Ah okay, thanks. Like I said, she is very responsive and we are getting to the point where stopping and backing all I need to do is shift my weight and she reacts without having to pressure the bit. Turning/neck reining she is progressing, but I am not going to rush her. She will rein without a bit in and just using a rope around her neck, but stopping that was is another issue. When she realizes there is no bit to back up the stopping when she doesnt respond to the weight shift she will just go go go haha.