PROs: Well, for one thing, it makes for a very quick session.  Also, the idea behind it is that the ideogram is your first and most basic line of communication to your subconscious mind, so, in theory, at least, it should be the most dependable.
CONs:  You have to be very good and accurate at your ideograms - that means that you have to practice, practice, practice and develop them.  Establishing that direct line of communications takes a lot of work and practice.  Once you have developed it, though, using it becomes a clear path to your intuitive ability.

It's good to develop your ideogram language, and as you get more experienced, that will happen naturally. The more you develop it, the wider range of targets you will be able to view. I would caution you, though, to remember that the ideogram stands for a >>gestalt<< (the basic aspect of something) , not a noun. For example, "water" stands for the basic aspect of "water-iness" (liquidity) of a thing. As such, you may get the ideogram for "water" when the actual target is, say, either a cloud (made of water), or a can of gasoline or any other liquid thing. So, watch out for ideograms such as "sky" and "mountain". Understand that the "sky-iness" of something is not very different from the "space-iness" of something and that you might get the ideogram "mountain" for things like a real mountain, but also for things like an ant-hill, a pile of coins or grain, etc. Once you understand that the ideogram stands for the "-iness" of something (the most basic quality of it), then you realize that the first 8 ideograms Ingo created stand for just about everything you will get in "pictures-in-envelope" targets.

As for developing newer gestalts, there are things like, the value of something, the sickness/wellness of someone, the safety/danger of a situation or location, etc. So, if you are a cop, you would want to develop an ideogram for "danger". If you are a doctor, you would want to develop an ideogram for the aspect of "illness" in a person. In the context of using ARV for gambling, stock market, etc., you might want to develop an ideogram for the basic quality of "value" and see which of the targets you view for any stock trading day is the one that has the basic quality of "value-iness" for you. The main thing is that you develop ideograms to suit your own personal applications and needs, not just to create a bigger, physically-oriented dictionary.

That often happens when people have strong natural ability. It is often surprising to some people who have never believed that they have the natural ability to find it suddenly coming out when they begin ideogram training. The way to handle this is: whenever the impression comes to you, immediately go over to the right side and write, "SC" (for S.T.R.A.Y. C.A.T. - that's covered elsewhere in this course) and write the impression down, then come back and finish the linguistic IAB sequence. If it happens again, then do that again. In other words, honor both methods. As you continue to train and practice, it is going to be your own subconscious mind that selects which one IT prefers as the method for speaking to you. Over time, you will score sessions, compare your impressions (both methods) to the feedback, and see which one of them gives the most accuracy. But do not discard either method for the other just because of some lesson plan or someone's advice on the internet. It has to be the decision made by your own mind as you practice and find out which way works best for YOU. Just be aware that the linguistic way takes more work and training, so the tendency is to take the easy way out and say, "Well, I'll just do it the easier way." But it is in going back after you get your feedback and seeing which way has provided the most accuracy that your conscious and subconscious minds can come to an agreement and decide which way is going to actually wind up saving that missing child, etc. Always go with the way that works to give you the most accuracy, not the way that "feels best" or is easiest, or is more in line with what you've always done or what someone else tells you they think is right. That missing child or that business or life decision shouldn't be determined on what someone else thinks is best - It is the results that count the most, and it is you who has to find out what works best - by trying both methods, comparing them to the feedback,and then seeing for yourself what is best for YOU. It can also wind up that you will use both methods as needed - one to get the generalities and the other when your mind wants to give you extremely fine details - almost like the nuances of understanding you have when you speak two different languages and each has a slightly different nuance of meaning for the same word.