I guess to exchange a medium laser (because lost or destroyed in combat or because you want it) against a small or large one is much easier than putting jump jets into them.

Even changing laser and autocanon would be hard. Why? Instead of a lot energy for the laser you need a lot of ammo.
So you suddenly need a place where you can store the ammo. Than you need a kind of transportsystem from the storage to the weapon.

That sounds like a major change to me and a lot of work. You'd need to reorganize the internal structure etc.

Now thing about jump jets again.You don't only need some in the feet or a part at the back to lift up, but a lot other to keep the 'Mech in the air.
Think of the wind blowing. Caught by the wind any 'Mech would just smash down if there wasn't anything to correct the jump right in the air.
If you want to turn a bit in the air you also need "mini jump jets".
Another thing why I wouldn't allow jump jets on any 'Mech espcially if there are any other customizations is the change or proportions and the weight.
Putting a part to an other place or changing it's weight will it make impossible to control a 'Mech while jumping.

But I remember Aidan Pryde had a Mad Cat with jump jets? So maybe it is possible (for the clans) but it would be a hell of work.
And it's nothing you can do on the battlefield.

I liked the way of customization in Mech Commander. I think you had diffrent slots: energy weapons / weapons which needs ammo / missiles.

My experience with MW2 and MW3 was that if I could do 63 points of damage with an alpha strike, then I could blow someone's Left or Right Leg off = dead mech.  If I could do 53 points of damage with an alpha strike then I could blow out any mech's Left or Right Torso = dead XL engine mech.  If I could do 80 points of damage with an alpha strike then I could blow out any mech's Center Torso.

This is fairly easy to do in MW2 or MW3, the answer, fusillades of medium lasers (especially ER Mediums).  The Nova (Blackhawk), has 12 ER Medium Lasers = 84 damage.  It can run up to an Atlas (quite easily), fire once, and kill it.  This is not how the board game works... at all.

In the board game, all of those lasers are probably going to hit different locations.  Infact, if it hit with all 12, then 2 of the lasers should hit the CT, ~2 to each side torso, ~2 to each leg, ~1 to each arm.  This is why big weapons like AC/20s and Gauss Rifles are good, they concentrate damage.

Now, since no mechwarrior game has solved the chief problem of translating the numbers straight to a sim (that problem is the random hit location table) you end up with a game, which in my opinion didn't even consider this issue, and it is even more twitch than MW4.  One shot, one kill = boring.

MW4 also did not directly address the issue of no random hit location, but they did look at the weapons and think, "Wow, wait a second, we can't just translate the numbers straight in, that makes fast recharge weapons with good range (i.e. ER Medium Lasers), really friggin good."  So they boiled it all down and built it back up so that it would be a fun Sim experience and not a direct translation of the board game numbers (which only work with random hit locations.)  Is it a perfect game?  Hell no.  Especially after the MekTek releases we end up seeing even more damaging super long range guns, pushing the game closer and closer to the gameplay that I remember from MW3.  One shot, one kill = boring.

Now that I have defended my point, back to jump jets.

I agree with zeus * I hate forum time outs* anyway, I agree that mw4 started some gayness to the battletech universe.  with jumpjet problems and deuseifying the med lasers, small lasers, machine guns and small arms.  If they had a little more kick to their attack like if they were all combined in 1 shot that would make a mech have trouble shooting back, it would improve useabillty,
anyway, Jumpjets could be altered in a way so that if shot while in the air, it can have a possiablity of making your mech fall over on the way back down, damaging your parts, along side that your jumpjets can give of enormus amounts of heat, (since it is lifting 30 or more tons into the air 10 or 20 meters.) its just an idea

The only way you will see any type of balancing is if you include logistics into a game.  Some weapons are easier and cheaper to produce while others are correspondingly more expensive and difficult.  Until you have a mechanism in place to represent this players will always take the cream of the crop.

that only came up in mechwarrior 4 mercs when they tried to rebalance the guns.  Still though, not quite enough to offset the massive preference for clan gear.

Maybe if they factored in money in terms of customization then players simply couldn't always afford decking themselves out in the top o the line stuff.

yeah that sucked.  I throw my madcat mk2 off the top of the megacorp building and what, just a slight stumble?

PPL as in Photon Propulsion Laser ... photon laser push any object it hits by its own momentum, yet this is a very shortlived force...
Microwave Lightcraft / Laser Lightcraft Tests
Beam Powered Propulsion
Photon Powered Propulsion
Antiproton Annihilation Propulsion

The JJ´s efectiveness should depend on the tonnage of the ´Mech, so the lighter Elementals do hop-around-like-a-bunny, but the real ´Mech should be limited in this, as in MW! And for the Assualts/Heavy ´Mechs it should only be for the purpose of avoiding attacks.