I don't see much key man risk in the traditional LIC's. Maybe of these 5, I rate Frank Gooch at MLT the highest and if he disappeared it might leave a gap. The risks I see are - NTA discounts (even if you're buying at a discount, it could get bigger), concentration risk. These LIC's are even heavier in the banks than the index itself. There are so many other products now both ETF's and LIC's that help you diversify, some examples I've posted about and hold include MVW, EX20, MVS (ETF's) and PIC. I also hold ARG of the five traditional LIC's mentioned. There is nothing wrong with them at all, especially at NTA discounts, but I'd just pick one or two instead of all five, and then add some other products that improve the diversification of your underlying investment and avoid having all your eggs in the traditional LIC basket (unlikely but just in case).
I don't think you can look at the franking of VAS vs traditional LIC's in isolation. Even more so as a driver to decide your asset allocation. You need to think about total returns - capital, income, tax. Not just one aspect of tax. The key reason to invest globally is access to a whole raft of companies like Google, Amazon, Apple, Facebook, etc that you have no hope of accessing in the Australian market which is 2-3% of global equities. The Oz market is very small and very concentrated. Historically it has held up very well versus global indices but that may not be the case forever, so these are the factors I'd be thinking about