You seem to have two main questions here, asking if RISUG exists and if so, if it is safe and effective. I will answer each in turn.
Does RISUG exist?
There is little question that RISUG exists, as there is an abundance of evidence.
There is a patent filed in the US which shows at the least that the design/technique exists(1).
There are several peer reviewed studies introducing and exploring RISUG(2), (3).
RISIG has been reported in numerous credible media sources such as Forbes(4) and Wired(5). If RISUG did not exist it seems likely that it would have been exposed by now with a retraction printed.
There are clinical trials currently underway in India(6).
It is currently undergoing FDA trials in the USA under the name Vasalgel(7).
Is RISUG safe?
There have been a lot of studies done so far based on a number of clinical trials on humans and animals. While the results may not be conclusive, it certainly seems that RISUG is as safe and effective as claimed.
A 2001 study(8) found that “the intervention of RISUG in the vas deferens even for a period as long as 8 years is absolutely safe and does not lead to prostatic diseases.”
A 2005 study found that(9) “SMA vas occlusion and its non-invasive reversal do not damage the accessory reproductive organs.”
The results of a 2003 study(10) on langur monkeys found that RISUG does not cause sperm granulomas to form (a reaction of sperm leaking into surrounding tissue) which can be painful for some men.
The results of a 1999 study(11) indicated that the vas deferens returns to normal after the removal of RISUG. These results toger indicate that RISUG has less of a health impact than a vasectomy does.
As far as reversing the procedure, a 2005 study again using langur monkeys as test subjects found reversal was safe without adverse side effects.(3)
All the studies so far show no adverse reactions or side effects and far less of an impact on the reproductive organs than existing methods.
In addition to all of that there is also the possibility that RISUG could prevent the transmission of HIV to partners, which certainly would do a lot for health in general(12).
Is RISUG effective?
As far as effectiveness goes, it seems that RISUG takes effect almost immediately and is successful in inducing azoospermia.
A Phase 2 clinical trial conducted over 12 months found that all test subjects had azoospermia . No pregnancies were reported and the method was considered safe(13).
A second follow up study from 1998(14) had similar results to the 1997 study, except this time the method was shown to be effective for a two year period.
Finally, in a third study from 2003(15) performed on a group of 25 men, six of the men developed azoospermia within the first month, an additional 15 in the second month, with the last 4 men following in the third and fourth months. No pregancies were reported over a six month period.
All signs point to yes
All the evidence we have so far indicates that RISUG is indeed safe and effective. It looks like it should be appearing for use by consumers in the next few years in the USA if the FDA trials go well.