I have dabbled a bit with pyro skilling lately. I'm just in it for a few extra HP and to stay in my Mayhem category (rifle).
My take:
PROs with Mindforce
* Fun (cooler effects than rifle/pistol)
* Arsonistic chip is useful to max
* It's easy to get psyche to 50-60 (contributes to HP and e-penis)
* If you care for bioregenesis chips, MF skilling will help to raise bioregenesis skill (partly common skill pool).
* Some HP to be had from concentration, power catalyst, mf harmony , force merge, bravado
* Possible to unlock/max out uber FEN chips @L70.
* Some MU on skills (1200-1300 % atm, but dropping) - not useful for me, but for FEN users probably
* When I use combustive chip together with my cthulhu Shade armor helmet (the only ingame?!), the eyes of the helmet starts burning!
CONs with Mindforce
* No Coolness, Combat sense or commando (no HP /defense)
* UL amps are rare (and expensive)
* Biggest L amps (27-36 dmg) have high MU (135-140 %)
* Hard to find a steady supply of L chips at higher levels
* UL chips also not many of on market
* no Armatrix line of chips
* If you haven't unlocked Wounding prior to skilling, unlocking mf harmony and power catalyst takes more time.
* No chips (CDF edition) to trade from the Daily token vendor (Calypso)
* No mayhem amps for chips
* Guns are better suited for Mayhem due to bigger amps and tailored DPS.
TLDR;
Guns are good for HP increase, availability, large selection of UL weapons and UL amps. MF is good for some HP gain, visual effects and possibly a fast route to uber 87 DPS FEN chips.