The M4 in its 14.5" configuration is a near ideal compromise between length and performance. Naturally a shorter OAL equates to lighter weight, improved handling and superior confined space movement. Plenty of people are dead thanks to the M4 and it's 14.5" barrel, it works as advertised.
If we discuss training issues then we need to discuss what isn't a training issue. Fixed LOP is not a training issue. Non ambi use is not a training issue. Lack of rail space for designators, lights, NOD's etc is not a training issue. The fact this rifle weighs more than an M4 is not a training issue. The risk of serious injury due to the chamber being rested against your face(think catastrophic case failure or squib) is not a training issue. The horrible mechanical offset(the F90 isn't the worst offender, the type 97 and Tavor are atrocious) is not a training issue. These are real problems that are unique to all bullpups and their "cutting edge" design. The only benefits a bullpup has going for it are better balance and a more compact package when compared to similar length barrels in other rifles. The negatives listed above far outweigh those two benefits by both numeric and practical values. Entering and exiting a vehicle with a rifle of any length efficiently and effectively, is a training issue. One handed operation is far from the norm and not difficult with an AR or similar conventional rifle design, regardless it too is a training issue.
TW25B
Many of the negatives you are listing off aren't major drawbacks in the practical real world. At one point, I might have agreed with you, put my personal experience shooting the T97, Tavor and AR's, has told me different.
Fixed LOP on a bullpup is a completely different issue than fixed LOP on an AR. I'm a short guy, and I usually run my AR stocks only one click out, sometimes two. I like the stock nice and short. However, and I was also surprised to learn this at first, the fixed 15inch or so LOP on the bullpups does not hinder me whatsoever, in fact it feels incredibly natural. This is due to the drastically different weight distribution and balance vs an AR. Fixed LOP on bullpups (at least the ones I have experience with) is essentially, a non issue for most people. If anything, very tall people may find the LOP too short, just look at Hickok 45.
AR's are not exactly ambi friendly either, yet guys make do just fine. If you are a lefty, the Tavor and most modern bullpups can be converted for dedicated left hand use, easier than an AR can. If you have to switch shoulders, it can be done just fine, in fact I can always switch shoulders faster with my Tavor than my AR's. Firing off hand, not a big deal whatsoever. Be aware of the ejection port. Some rifles (F2000, P90, RFB, RDB) solve this issue completely in their own way. If you're in a full on firefight, a little brass wisking by your chin is the least of your problems, it's an annoying distraction at best and it's not like you'll be constantly shooting offhand. Again, a relatively minor issue (but issue nonetheless I grant you) being blown out of proportion.
Lack of rail space? Easily fixable, just look at the Brits L85A2. I have a Midwest industries extended handguard on my Tav. Believe me, boatloads of railspace for every toaster and can opener you can imagine. A stock C7A2 has even less rail space, so..
Weight? Weight on my Tav is very comparable to my 16inch DD when both have an optic and light, with the DD being just slightly lighter. My 20inch AR is heavier. Only my 11.5 AR is noticeably lighter than my Tav. The Tavor is generally a little heavier if you place them both on a scale naked sure, but the Tavor is basically a full size rifle in a package as long as my 11.5 AR. It's not heavy by any means compared to other rifles I own, and certainly a non issue for troops training with it 24/7.
The supposed risk due to the chamber being closer to the face is completely unproven, the one vid I did see of a FS2000 blowing up didn't injure the shooter. If it was such a problem, then armies like the Brits, French, Aussies, NZ's, Austrians, Israelis, etc, who put thousands upon thousands of rounds thru their rifles, surely would have made this well known. All I ever hear about it is internet theorizing by people trying to find reasons to hate bullpups.
The higher offset is indeed a training issue, just be aware your offset is a little higher? Again, for troops or anybody who shoots/trains with a bullpup all the time, it would be second nature.
I'm not claiming that bullpups are saviours of the world or anything. I'm just pointing out that they're a very solid and proven concept that catch a lot of flack for simply being, different than the almighty AR. If you are willing to adapt yourself to the rifle and learn it, it's advantages become abundantly clear. If you simply refuse to adapt yourself to anything different, then yes, different styles of firearms will forever be unusable to you. My personal experience has shown me that a bullpup that's designed and built right, like the Tavor, will go toe to toe with any short barrel AR, and it runs way cleaner too. The T97, while not a bad rifle, falls well short of the Tavor.
If you want a genuine drawback to a bullpup, it's that they generally fall short on accuracy when compared to an AR. Triggers are usually not as "target shooter" friendly either. AR's are also more configurable and modular. Everything else, can be adapted to through training and practice.
