Well in psp2 casts had the best pp regen, so it was somewhat viable, if somewhat weak. In Ifinity, with tech costs lowered down, all races receivig pp regen boost if i'm not mistaken (maybe surgeon Weyu can provide some numerical data here as well) - newmans became force kings.
Now, to be glass cannon your damage output must be highest among the other races, and they only are second, so, the only way for them to be damage kings is with the use of Infinity Blasts, and only if they provide the biggest damage output of all the Photon Blasts. Imo - Nanoblast is the best Photon Blast, since it gives you invulnerability for you to go on a rampage and direct damage. Other than that - they seem more like a 'challenge' race for advanced players.
Hah. it's easier in most regards. Maybe it's because i played force in psp2, but i only noticed eva when using dagger (hidden eva boost from rarity). PP was gone after few casts, etc. Cast ranger was easiest for me to play in psp2, laser cannon burned through most of story content. Aside from that - in infinity you get more ability customize, there is an ability for VAN to get back part of lost trap power, and with rebirths, fusion, inf. weapon extend you get crapload of power, not to mention new techs useful even for melee classes, like Foverse. More shield damage, perks for perfect blocking that extend window for pb, heal you and restore pp. I consider Eva reliance a thing of psp1, since psp2 introduced dodging and blocking.
I haven't been playing Infinity much, since it's still in japanese, but i got to level 70+ on Newman Force, and it was a breeze compared to vanilla psp2. Played a bit with cast ranger - don't run out of PP as fast as in psp2 as well, i think charge shots cost less as well.
UPD:
http://www.bumped.org/psublog/psp2i-demo-photon-art-balance-and-weapon-changes/ Some info on balance changes, and it seems that Duman Infinity Blasts do gain power as they increase type levels.