I think that collisions on both ends is a good idea.
Not because it would diminish HO's... I mean, if you know the current system will make one of you die and the other one live, are you willing to take the 50-50 chance it will be you? I see no difference if it was a 100% chance you'd die from collision, both players will still end up in a HO situation.
I believe its a good idea because the current system CAN be abused on purpose. For example, I can make a buff player's FE think he collided with my fighter, blowing him up. But on my FE there was no collision, so im untouched. I've managed to make 4 buffs blow up one after another like this after I ran outta ammo on my 38. 'twas the day I figgered how to do it . And its sickening.
If both sides die in collision, neither side will have any advantage, thats the way I see it. If im gonna HO, ill HO dammit, I dont care if i'll collide. Just knowing that theres a 100% chance that we both will die in the HO only makes for a more interesting game of chicken.

Edit: Gah, this is what i get from reading 2 threads so close to each other.. mental overlap. what the heck.
On-topic:
I dont know what HTC has planned to address some of the possible abuses of the 4 buff system, so far I can see:
1) 5k alt mass buff formation not caring about field acks (they dont do now anyways) smashing a field to pieces and then acstarring it to death.
2) Ackstars. Up 4 buff flight of B17... and well, have 3 people do the same and your base is as good as saved. Similarly, a grass cuting buff formation blasting away at a field's defenses and vulching with the buff formation
3) Killshooter: Ermm.. if I dive in between the buff formation and the human gunner shoots his own planes as he follows my plane... does killshooter apply or do the bullets do no damage (Booo!) or do the bullets fly through the buffs in formation (*grrrr*)?
4) FPS : 5 people up 4 buffs each.. get them into close formations.. will it be warp gallore, making their buffs virtually untouchable.. or what?
5) Buff guns: We heard the shoot-through fuselage deal was fixed. But then again, now the buffers will have 4X the guns to shoot at, and if they allegedly work the same as our buffs now... what fighter will possibly get even close to such concentrated firepower? (since all bearable guns would fire at same time at same target).
6) Buff GUNNERS. Will the buff guns be modelled to die to a few hits (like ki67)? Or will they still be ROBOCOP units manning the guns (other buffs)?