I love the mid-lengths and the good news is that more and more aftermarket parts outfits are producing goodies for our little mid-length wonders (My hat is off to Sinistral and the good folks at CavArms, who are now producing cool new middy furniture in Marine Brown.) Knights and Armalite are now making railed free floaters for middy's, heck, it's good to be free American and a middy owner.
I can hardly wait for Armalites M-4 type chrome lined middy barrels to start popping up in builds here on ARFcom. This new barrel is very likely to end up as the heart of my next rifle build, I can tell you that.
I had owned several Colt CAR's over the years and always wished for a little more handguard, but less than the full length 20" ( I still wanted the easy to manage indoors 16" inch carbine, but with a little more room up front to mount up things like Harris pods and flashlight mounts and still have enough free space tward the rear of the hand guard for proper hand placement without the clutter one comes across when trying to put all that stuff on a CAR length handguard.)
I to belive that the mid-length gas tube is finaly the right impulse length. Unlike the dissy's which still have the CAR length impulse (Yes at first glance Dissy's would seem to be the answer, Even longer sight radius and even more room to hang stuff on the end of the rifle. How ever dissy owners and builders have their own set of problems, Not the least of which is that they if they want Chrome lined, are just as tied to one company, Bushmaster as the people who are waiting for Armalite's Chrome lined near M-4 weight middy are tied to Armalite. That and the fact almost nobody is able to build Light weight M-4 dissy's because Bushmaster only orders like 5 of them at a time and tells you when you try to order one, that you might actualy receive your ordered barrel some time before you die. Otherwise you are stuck with the dissy heavy weight barrel or one of the many non-chromed heavy weight dissy barrels out there (that is unless your willing to shell out the bucks to send your barrel of to Kurt or someone like him, to turn your barrel down to a lighter profile, but with the dissy this sort or barrel turn down is not quite as easy as it would be for the middy, as the dissy still has to have the hump half way down the barrel to deal with the CAR length gas block under the handguards.)
The middy gains a slight weight advantage over the dissy from not having to mess with two gas blocks and is cheaper to produce. ( I know that my RRA non-chromed middy upper from Norala Tactical came in a heck of a lot cheaper with the bolt assembly than any of the Non-chromed Dissy uppers out there by nearly a hundred bucks.)(Sableco has the RRA non-chrome middys for just about as good a price.)
I like the idea of the middy handguards providing a little more protection of the barrel both from the standpoint of keeping me from getting burned on a hot barrel (This has happened to almost all CAR length shooters at one time or anouther and I'm no different and the fact that the more barrel you have hanging out there on the end of the rifle, the more likely you are to bang the hell out of it on some thing like bricks or doorways while operating closed confined spaces or just looking for a rested shooting position. Its a lot easier to replace $18.00 hand guards, than it is to replace banged up $199.00 barrels. The longer handguards are cheap CQB shock absorbers for your barrel.) (I'm sure this whole idea has the guys at CavArms rubbing their hands with glee.)
Just my two cents worth on covering some of the advantages of the middy that had not been covered in this thread so far.