on that note, i suddenly notice that everyone apparently hates the chunky salsa rule, why is that?
The problem is that grenades damage went up with 6 points, but their damage drop-off has remained the same. This means that suddenly Chunky Salsa happens far more easily, AND the grenades are far more lethal while we're at it.
If the HE grenade exploded 1m to your left, and 2m to your right was a wall, then a HE grenade would do 8P+0, because 1+2+2=5 so no rebounding blast to hit you. If it exploded 2m to your left, and 1m to your right was a wall, it'd do 6P+2P, so you'd eat 8P/-2. Nowadays, that 8P/-2 has both parts of it boosted with 6, so you're facing 12P+8P, meaning you get hit by 20P/-2. And in the first situation, which had 8P+0 in SR4, you'd now take 14P+6P, so also 20P/-2. Now Armor might have increased, but that only gives you perhaps 2 extra hits on the soak, while the damage went up with 12. So you take 10 points extra damage due to Chunky Salsa.
Another situation: You're in a sidestreet that's 6m wide and the grenade explodes in the middle, while you're 1m away from the wall: In SR4 it'd go 2m to you and hit you with 8P, 1m, rebound, 1m, 4P, and vanish before it reaches the center. Same for the rebound from the other side, which takes 3+3+1m to reach you so the blast stops before it can reach you, you resist 12P/-2.
Now the SR5 scenario: 2m to reach you, 2+2m to reach you again, 2+2+4+4m to reach you after that is too far so this side of the blast hits you at a 2m drop and a 4m drop. The other direct goes 8m before reaching you, which means the HE grenade BARELY dropped. If you had been a bit closer to the grenade when it went off, you'd get hit thrice by blasts. Now you simply resist the same 20P/-2 from earlier, with the same consequences, and if you had been slightly worse out of position, it'd have hit you with even more.
A Fragmentation Grenade, meanwhile, in a 12m-wide street, would hit you thrice. If you're 1m away from the wall and it explodes in the center, we're talking a 5m drop, 7m drop, and another side with a 17m drop, so that's 18x3-5-7-17=25P/+5. In SR4, it'd only reach 12m, so it would only hit you with 12P/+5.
And this is outside scenarios. Inside an office or a corridor in a corp-facility...
There are, however, easy fixes to this. First of, a GM can houserule that Chunky Salsa counts as overlapping explosions, so all but the strongest hit are halved. That'd change that 25P/+5 to a full 13P blast, a secondary 11/2=6P and another secondary 1/2=1P, meaning 20P/+3. The 20P/-2 from the earlier scenario would become 16P/-3. Still painful as hell, but less of an instant-killer.
Second, Chunky Salsa only works when the barriers last. However, let's face it, construction is cheap. Those office walls? Those would be drywall, so the grenades easily tear through it. You're in an alley and the GM doesn't want to murder you? Well, he could always have a few windows look out into the alley, and the blast now channels through a really cheap window and destroys someone's living room. So then only exterior walls without windows become a real problem for Chunky Salsa.
Third, even with the new matrix, people are paranoid about wireless. So Wireless grenades would nearly-never be used, because if a hacker gets into it, bam, you're dead. Even people who only turn them on before throwing them, would be vulnerable if a Hacker got marks on their PAN before and now sets it off with an out-of-turn Free Action. So nobody would use these, except for corporate hit-squads with DR7 comms and a decker on their side.
Motion Sensor grenades, meanwhile, are dangerous as hell to anyone who does not have a really good Throwing Weapon skill. So gangers would never use these, meaning that nearly never do you have to worry about any grenade other than a timed one. And Corp Security would NEVER throw grenades (or even be issued any) indoors due to collateral damage.
There's also one other thing: Run&Gun now has an Interrupt Action where you can run away from a grenade. Of course that means they still flush you out of cover, but unless your enemies got a LOT of grenade throwers, you're likely simply walking into a firing zone without dying horribly.
Anyway, with those things in mind, keeping use sparse, keeping chunky-salsa risks low, and giving the players the time to get scared and scram, grenades still are lethal, still are very dangerous, still put you at significant risk, but lose the ability to wipe out an entire party without them having any chance to get out. You're in a basement and the door in front closes just after a few grenades are thrown through? Take the Initiative hit and run back around the corner, so you don't get massacred by the blast. Even a Motion Sensor grenade would no longer be an instant-party-wiper unless the party is dumb as bricks and ran out of movement allowment.