Regarding the matter of multi-flash operation of the Speedlite 430EX, I posted an inquiry on another forum directed to the attention of Chuck Westfall of Canon USA, their Technical Advisor.
The Canon Speedlite 430EX is not shown by its manual as providing a multi-flash (so-called "stroboscopic") mode on a "local" basis. However, the manual (p. 27) indicates that this mode may in fact be utilized when using the flash unit as a slave in a Canon wireless flash network with all "Type A" bodies and most "Type B" ("TTL") bodies.
Is this in fact true?
Yes. It requires a master unit that supports MULTI flash, such as the 580EX II, 580EX, 550EX, or the EOS 7D's built-in flash. (PS: The 60D and T3i built-in flash units can be used as master units, but they do not support MULTI flash.)
In another forum it was commented by one correspondent that the multi-flash ("stroboscopic") mode could be invoked (via the camera flash control menu) when the 430EX was used on an EOS 7D body, but not when used on an EOS 5D Mark II.
Is there in fact ever the opportunity to invoke multi-flash operation of the 430EX (other than perhaps as a slave unit in wireless flash network operation)? If so, in connection with which EOS bodies?
The only way to achieve multi-flash operation with a 430EX or 430EX II is through use as a slave unit in a wireless flash configuration controlled by one of the eligible master units listed above.