I've used this method a number of times in South Africa and have been meaning to give it a go myself in Ireland. There is no question about it, you will put a large bait much further with this method.... SIMPLE
The method itself takes some practice to slide the bait out but with practice you should be able to put a bait as far as you can cast....
With that comes the problems... In South Africa and Mozambique the tide flows on the shores are almost nil. There are small fluctuations in HW and LW so there is a significant reduction of drag on the lead. Even with this the guys use 8oz and 9oz leads to slide the bait out. Given they are sliding whole Bonito or even bigger baits, but I have seen 9oz used for sliding whole Mackerel in a heavy surf.
I think in Ireland you will need to use fixed grip leads or try to get a hold of some 8oz or 9oz grip leads... at the very least 7oz fixed grip leads would be the minimum to try this method. Even then, don't be surprised if the lead is moving on you. Try it during neap tides and go from there. Make sure there is no weed as it will also trip and move the lead. For Tope use the sliding clip with the weight as this will help greatly when sliding the bait out, especially with a lighter half Mackerel bait. Make sure you use a 8/0 short shank style hook minimum to help keep dogs from hooking themselves up and ruining all your hard work.
Let us know how you get on! and any more questions, fire away.
Kev