thanks for posting the reply from your webhost.
To be honest, I feel that this is totally BS*.
Every webhost I had to deal with about this was capable of changingthat limit (which is easy and not even that security relevant...). Of course it is easy to say for Host Europe to say that the script should split up the POST request variables, as it is the most comfortable solution for them. Unfortunately, this is absolutely not easy for me to do, as it has some severe implications on other things within the plugin.
So, this means: I will definitely look into a better way of dealing with large tables, to get rid of this problem (not just because of you, but because of everyone who has this problem (but might have a more cooperatative webhost)). Unfortunately, this will take some time, as it requires some major plugin restructuring and testing.
So, until then, I'm sorry to say, it seems that you won't be able to use such large tables efficiently on your webhost :-(
(You could still work on them offline in Excel and export/import the changed table to the plugin.)
* Lustig, dass BS sogar als Abkürzung für Blödsinn geht.