With my experience with 3 more inches being the start of bindage, I would say that the 1 to 2 inches you get out of flipping the mount is inside the danger zone. I would also say that if you put a 2 inch spacer in front it will lift it 3 inches so you will lose an inch or 2 of down travel from stock.
You need to measure the amount of clearance that you have at full lock to lock, it makes a huge difference, also you need to make sure that the shaft isn't dropped into the spline as that gives a false reading too. I'm not saying your wrong but I don't know anyone else that would advice more than 1 1/2 to 2". I measured mine at a little over 2 ". I ran 2" strut spacers for 25k miles and a lot of off roading and never broke a CV, others, inculding Digger, have had problems with 2" spacers.
The strut top mount is only 1" thick and the mounting is offset so the total drop you get from it is only 3/4".
In stock form I only had around 2.5" of down travel, that was on a nearly new (6K miles) vehicle so it had good springs, you might have a bit more with older springs.
Personally I think that anyone doing their own mods should take a good luck at what they already have. Measure the wheel travel, measure the static sag, pull a spring off (it doesn't take long). Swing it from lock to lock and raise and lower the suspension at the same time. When you're confident you really understand whats happening then decide what mods are going to work and what isn't. Aim to keep at least the same amount of static sag as stock.
On the rear raise and lower one side at a time so you see the arc that the tyre travels in.
