The only change that should be made to Stamp Duty is that the bands should be tiered, so that crossing a magic threshold does not result in the total stamp duty rate doubling. For example, the first €200,000 could be stamped at 4% and the next €200,000 at 8%.
Any reduction to "help" FTBs will have little or no effect, since the total purchase cost (price + stamp duty) will remain the same.
There might be some merit in replacing stamp duty with an annual residential property tax (including sites zoned for residential use!). This would support the market in the short term, and in the long term would discourage speculation, increase supply, and lower transaction costs. Unfortunately I can see this being difficult to implement, for political and practical reasons.