I'd go with the one Gwyn Lewis sells:
SUSPENSION
Reason being they are recessed to the spring has a proper seat to seat in. The ones from Flatdog don't look to have this.
And importantly the fronts Gwyn Lewis ones have extra large holes to allow plenty of movement of the front shock, to avoid it fowling if you also increase axle travel. Remember the front shock sits inside the spring.
As for issues, you should see none. But what you may find is that you get cross axled easier. This isn't because you have less total travel, but you'll have less relative downward travel, because with the lift, the shocks will already be extended.
This is fine if you don't plan to off road loads, but you may find it a compromise.
Extended shocks will sort this, but as this will give you more travel, you might want to look at extended brake lines too. And more travel with a stock springs means they might fall out of the upper spring perches. So dislocation cones or longer springs might be needed.