great. i have run with and without tuning, with and without modded solenoid.
the modded solenoid affects ONE shift-that is the 3-5. because reverse engagement uses the same solenoid so you may feel a difference that but it is not a "shift".
what i think you are missing is that the reason flares are prevalent on the 3-5 shift is because so much is going on in the trans. the third gear clutches must be release prior to the fifth gear clutches engaging. if you have a built trans, plus good tuning, plus a modded solenoid you end up with binding which breaks hard parts. that's not usually good for the transmission i've heard...
carry on