Two different branches of the simmons design tree with the same basic ideas within them but a different application.
It's interesting how influential Richard Kenvin and his championing of Simmon's ideas has been over the last few years in terms of board design outside the thruster realm. Although you could argue that the recent trend to shorter wider thrusters has some roots here also!
Before Kenvin's original simmons replicas no one was really using the concepts Simmons came up with all those years ago, with the possible exception of the hull crews and whilst related, they are very much a different type of craft. Since then, more and more shapers are offering some kind of take on the concept.
Take these two, both definately directly inspired by Kenvin but neither direct copies of the original "casper"
On the left is a 5'2 Tyler Warren Bar of Soap. The shape originally came from Tyler making a small version of the original "casper" mini-simmons for the daughter of his father's friend. It came out so well, he kept the first and made her another! Hands down the favorite board i've owned to date. It has the chracteristic short wide mini sim style but with the wide point pulled aft of center, snub nosed with a wide tail block. It's stringerless with two very wide based keels which owe more to a conventional keel fish than the half moon simmons style. The bottom contours are the classic simmons bellied entry into flat but through the fins theres vee and deep double concave (spiral vee if i remember correctly!) The rails are soft in the front third but pretty hard through the fins and pretty thinned out. In the water it's fast and lively, very responsive, probably best described as a fish with afterburners. I've overtaken people who've dropped in on me on this one on more than one occasion. Although it's still a lateral style board it's looser off the top and goes more vertical more easily than the other mini sims i've ridden.
On the right is a 5'6 Jeff McCallum Mford. Named after Jeff's tattooist mate Milford Barnes, he asked Jeff to make a board that felt like floating on a cloud (allegedy - it's unclear how many ales had been consumed at this point!) Jeff is credited with making the second ever mini simmons and is part of the same san diego surf scene that spawned kenvin. This board takes the bottom contour and the rails of the simmons but marries it to a template based on Greenough's velo kneeboards with a widepoint forward and a narrower tail block. The fins are quad half moon keels and the deck is concave. The rails are softer and rounder than the soap but still follow the same high to low shape. Bottom shape is still bellied entry but very quickly goes flat for most of the board with a medium single concave through the fins. In the water it's more idiosyncratic to surf, smoother and more flowing through the water, more lateral, more hull notes in there. It's wider and a bit flatter and goes better (brilliantly) in junk waves.
There are lots more variations on these ideas out there. Mccallum himself makes at least two other shapes based on the simmons idea, Royal makes his Simzers, Baugess makes copies of the original casper and bing, zamora and christenson all have versions. Unfortunately hardly anyone over here has jumped on board although dale walker and Tim Mason have been making some, steve croft at empire has his lumus model (a bonzerised quad version) and Nineplus have one in their new Hasu range thats out soon . It's only a matter of time before more shapers do, they are superbly suited to our regularly average waves and a whole heap of fun!