Not sure how clear I was in that older post, nor am I sure if I answered the guy's question.
Few boats will not benefit from imposing (via the standing rigging) about 1-1/2 to 3 degrees of mast rake. The great problem so many people have is that they fail to properly tension the headstay after the furler is installed. Furler extrusions are heavy! --and all of them require additional tension to keep the headstay tight. Sometimes this added tension can be enough to break something else; and it is not uncommon to break stemhead fittings or mast cranes, especially on older boats when the headstay itself is far older than the newer furler. Worrying about this, many people tension the headstay to only where it was specified to be without the furler; and they sail around with sagging headsails and complain that the boat won't go to windward as well as they'd expected.
Perhaps worse is when the forestay is replaced with the furler and comes up, for whatever reason, a little too short. I saw a Raider 33 like this and the boat actually had forward mast rake. I wonder how those people ever tacked the boat at all.
By 'prebend' I assume you mean a progressive rake angle, more above the spreaders than below. I would not impose 'prebend' on a cruising boat with a masthead rig. What would be the purpose for this? A 30-year-old Hunter 30 is not a racing Star. Few people would realize much benefit from a move that inordinately stresses the 30-year-old mast, mast step and deck structure. If anything I would add a backstay adjuster, however-- especially if you have added a furler. I put one on Diana and I don't even have a furler. Keeping the headstay properly taut can never hurt; and allowing it to sag is like robbing your car of fuel mileage.
I would not, however, add more purchase than necessary to the backstay adjuster. I have 4:1 purchase and just got the idea (though have not yet installed it) to loop the line over a block at the bottom of the adjuster car and take it down to the other side rail, thus yielding about 8:1 (take away some for the slight angle to the legs; call it 7.5:1). But I would not advise using some kind of power advantage, an electric motor or, worse, hydraulic gear, on a boat that's not designed expressly for it. Some of those hydraulic systems could pull the transom right off the boat or shove the mast through the keel.
I agree with Ed and would tune the rig at the dock to include about 4-6" of standing mast rake. Measure by hanging a plumb-bob from the halyard and see where it lands on the deck. I see no reason for more than this; and having less (mast tuned in column) probably won't hurt but would allow forward rake if you haven't got the headstay, under the burden of its furler, tight enough. Remember to keep the lower shrouds taut as well, and to fine-tune the forward ones last.