If we are fed up with the strut on the foredeck causing hassle with the jib during a tack, how silly would it be just to leave the strut at home?! We only really need it to add power in medium winds only, don't we?

I'm assuming that you have a 1970's/80's hog stepped aluminium rig like Lucky Strike? The strut has never caused us any hassle. I have the attachment pins and split rings at both ends well taped over. When 2 handed sailing the traditional non tapered braided soft feel jib sheets are attached by looping the ends through a mid-point loop pushed through the clew of the sail - it looks as though it could slip but it doesn't - and when single handed I make the jib sheet continuous by knotting one end at the clew then leading it all the way from one side back to the other and finishing off with another figure of eight knot in the opposite direction. Both arrangements are 'clean' so unklikely to get caught up. 
The strut gives stability to the base of the mast. If you want to leave it out you will need to put a chock in the mast gate to hold the mast in its neutral position. If you don't you will have no control over the extent to which the mast will bend while sailing, i.e. you won't be able to set it up straight or pre-bent for initial conditions and the kicker will tend to flatten the mainsail rather than reduce the twist. 
The strut also stops the mast from falling over while the jib is being hoisted and lowered!

Did the forum collective ever decide if a strut the shape of a banana (but made of metal, obviously) would work the same as a straight one?
I can't make up my mind...

It's not nearly as efficient a shape Mags, if straight there is no bending force, it's all compression/tension, you would need a thicker and heavier bit of tube for a banana otherwise it would bend and not control the mast properly.

Watch out for JT's radical new "no strut, no lowers" rig, coming soon to a Championship venue near you (if you live in Penzance)...

Interesting.

Mike Jackson had a rig on his N12 with no spreaders, low hounds & a single main flattening control.  The mainsail was fixed at head and clew with a tack line that pulled on both the luff and the foot to flatten the sail as required.  Never tried in Merlins as far as I know.

Any one ever tried a Stump before?

Got a design on the computer with a stub mast up to gooseneck ... no strut, no lowers (or optional fixed struts) and room for a self tacking jib combined with possibly rotating the upper mast above gooseneck.

Alas I have been pondering this for a couple of years and not yet got to making the boat, ho hum, always this winter ...

Well on March Hare MR 1724? Mike went even further and did away with shrouds! I think he eventually fitted shrouds.

As to the sail control as you describe we certainly had that on Beat Nik 1523 and so did Pat Blake on Beatle Cut 1692? - Remember Jongkind Sails? Oh what a fuss. However whilst it certainly pulled cloth out of the bottom of the sail it did not control the overaul flow of the main, do the thing with a bit of paper and you'll see you need to control the position of the clew to effect the overall flow.

James Ramus (Stewart Jardines FD and Olympic Star Crew.) had a self tacking jib on his Merlin Rocket which was frankly a disaster. However it is fair to say it was not the quickest of ships either!