I'm an XT1 user and i don't know why you'd leave the K3?
I left Pentax DSLR back at the K200d when i needed/ *WANTED* something faster for indoor /low light sport...i "wanted" a reasonably and affordable good high ISO, fast shutter speed body combo...so the closest at that time was the Canon 7D...since i invested so much in that system (a lot more costly over Pentax weight and dollars) i stayed there into their FF offering now but the weight always was an issue...as someone always looking to move up in technology and with the wave of mirrorless hitting the market i jump onto the Fujifilm bandwagon looking to ditch the "bulky" Canon system but to cut to the chase...was it worth it?
No and yes....yes as i got a good system Canon to take those images i wanted for my sports photography....no, mirrorless does do well with everything but what my DSLR does better...in the end if i were patient enough i would have stayed with Pentax and saved myself a lot of monies
That's my story in short/don't read between the lines too much but i have no regrets as now i'm looking less at equipment and shooting more which i should have just been doing in the first place
Stick with what you have and make the most of it is where i'm at now.