Without claiming myself an expert in research on reading, and not a "speed reader" myself, I am probably able to deliver something of a lecture on this topic. Disregarding my lack of credentials, here's something you might find interesting in an unstructured manner. I apologize in advance for lack of sources; you can question me on anything I write, and I assure you there are sources but I won't bother digging.
Generally, proponents of speed reading don't know their stuff. Speed reading is based on the notion that the brain is underused in comprehending text; training would supposedly untap this potential. Don't count on it. Some say that if you read faster, you force your brain to focus, and so comprehension goes up. This works to an extent, noticeable, sure, but far less than hyped. And it is not a technique problem: it is a discipline problem. If you're generally focused at what you do, you're probably among the faster readers.
So most people read at about 250-400wpm, and this is related to the speed of the "inner voice," aka "subvocalization" (or, better, the phonological pathway/loop). So the idea is that if you reduce, or eliminate the inner voice, you can read faster. Programs that focus on these will claim 1000+ wpm. There is some truth to this, but these programs aren't all it takes.
Now when your eye sees text, it the brain takes time to parse it and register meaning. Conscious meaning, IIRC, happens after a 350ms mark, which means it is biologically impossible to read word by word, line by line, beyond the speed of the inner voice. This means that if you want to read faster, you're reading in blocks of text .
What does this mean? It means that when a normal reader sees a word, you're seeing a sentence or paragraph. Peripheral vision? Not necessarily. Peripheral vision doesn't have enough acuity to support parsing at a level required for detailed reading. IOW, most of the peripheral vision talk by these programs is BS.
The cases where PV is useful is when you have good familiarity with the text contours. How do you train this? The hard way: build your vocabulary, and read a lot. Reading is a "self-bootstrapped process," if you will. This is, AFAICT, the ONLY fool-proof, non bullshit method.
FYI, I recall two speed readers, who both read very fast but in different ways. First one reads blocks of text in a glance. He would see a paragraph and understand it in the time you read a sentence, in a kind of real-time, bulk-parsing process. The second one would read text in a "serial" fashion without regard to the meaning, into some kind of buffer, then think about it after he's done. The catch: both are geniuses.
The bottleneck in deciphering meaning from text is not at the text->parse stage (this is what SR programs focus on). It is from the parse->meaning stage. IOW, brain power. Fortunately you can train this, but probably not with some book or some program.
This is pretty thoughtstream. If you have other questions I'm happy to discuss.