most modern shimano groups are specifying no more than 16 tooth spread between front rings, as best as I can tell this does have an impact on shifting.
Also as best as I can tell shimano conservative is more with rear cogs than the front
with an 11-42 and 44/26 you would need a rear derailler that can handle both the 11 and the 42 and have wrap capacity of 49 (42-11=31) +(44-26=18)
play and push, but don't be surprised if shifting is compromised
and what ever you do, make sure big big works
__________________
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)