[hi19hi19]

One thing to watch for in 16th jumpstream, especially at higher BPMs, is repeatedly using the same arrow many times an 8th apart. Although not technically a jack, it starts to feel like one after a bit (I've been told this is an "anchor" which is a retarded name for the pattern but I digress)
It can be used to good effect, such as if there is a repeating sound you want to emphasize, but know it's also a lot harder to hit.
The top of the picture is an example of this on the bottom arrow.

Another tough pattern to watch out for is [12]*2*[12], with * being a 3 or 4, and the equivalent pattern in the right hand. This is another "anchor" pattern which really annoys people (bottom example in picture).



And as Patashu said, [12] and [34] jumps in jumpstream tend to be the easiest to hit, and one handed trills within the stream make it much harder.