JLI definitely do not need grenades. They are a scout unit that excel at long range, not to get in close and lob grenades, your general infantry have that job.
The grenades is there to protect them from being overrun, JLIR already have access to grenades via "infiltration tactics" in scavenger Doctrine and it hardly problematic, adding the Blendkörper will hardly create any issues.
Price/performance between pathfinders and JLI like I said is getting out of whack. Pathfinders are 290mp and new JLI are 250mp.
JLI do take longer to vet up through but they are capable of taking vet 3 pathfinders when only vet 2 (without sniper upgrade).
JLRI cost 250mp+45 MU.
Capable does not not mean probable, you can run some test (10 times) in cheat mode and see how it goes but since these units are not designed to fight each other their performance on vs other is not really that important.
In the end of the day what I have suggested is an veterancy overhaul meaning that the unit should vet at normal pace and if their veterancy bonuses prove to be too high then they should be toned down (or the performance in vet 0 should be toned down), generally speaking unit should balance in all vet levels.
If the argument is they can be equipped with bars, I'll remind you they are ment to Excel at range. If I wanted to equip units with bars, I'll just go riflemen.
Look beside vetterancy requirements being higher, JLI are just becoming blantently superior to pathfinders and I just hate seeing units that are similar become so different in cost/performance.
That is because you incorrectly assume that bar will not benefit Pathfinder in long range, BAR more than double the DPS of the M1a1 carbine so it a great long range weapon for Pathfinders. In addition the BAR spread damage across the enemy entities especially against 4 men squad thus making critical kills from scopes Garand more frequent.
My suggestions where not about increasing their performance but bringing them inline with other units (Veterancy overhaul, reinforcement cost/time, pop )and I actually suggested a price increase when they are being deployed via spawn.