Soundiver,
May not be the problem. Most european and american built synths are pretty bad, when it comes down to SYSEX bulk dumps.
But if you do find that Soundiver doesn't work for you - check out Unisyn.
I personally like Soundiver and use it a lot. But all of my synths are Japanese built, so sysex dumps are pretty quick and reliable.
As far as simple applications that load sysex and ,MID,
I personally avoid using little utility applications that just load .MID and SYS. files.
I stick to serious software.
There's nothing wrong with using LOGIC or Cubase or Cakewalk to do your sysex dumps. They are very well programmed, powerful sequencers, that give you enough resolution and flexibility to store and load SYSEX information.
ED
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A gentleman is one who never hurts anyone's feelings unintentionally.
- - - Oscar Wilde