6.7 more transaction bandwidth? Well this means more bloat and probably cheaper dust attacks, perhaps a candidate for a unit test because i bet by simply "tweaking parameters" you will degrade a security aspect od the underlying mechanics which are all assuming certain thresholds.. This is the problem with most devs in coins they simply do not understand software enough to fully comprehend what they are actually doing but just a get rich quick by trying to fool others that hey ive offered a betted alternative which is untested and probably full of hidden bugs of which are the worse kind.
If you're referring to fast block times being less secure it's no less secure than someone paying a vendor in Bitcoin and waiting only for the transaction to show up in the receiver's wallet (no confirmations). Vendors can't wait 10 minutes for every customer, let alone an hour. Users can set the number of confirmations to what ever makes them comfortable. I would argue that one quick I0coin confirmation is better than no Bitcoin confirmations since you know at least one miner has validated the transaction.
As for bloat, yes, the block chain grows faster, but many other coins have similar or faster block times. But with the recent introduction of pruning this has little affect on the average I0coin user. Users set the size of the block chain to just about any size they want.
Parameters are generally a balance between opposing, but equally important features. Security vs. tx times. Block rewards vs currency inflation. I think it's useful for different coins to have different parameter settings to demonstrate how they work in real world scenarios.