If you are going to run a mix and use solid wire, just stock the .024 consumables-
That machine will run out of gas with the larger wires- it won't run hotter or give you any more 'penetration' because you only have a certain amount of amps to work with and an .024 wire can use all the MM135 has already. Just turn the WFS up.
If you all-ready own some .030 or .035, just do a little experiment- max your volts and start doing some beads, weld a few inches stop- do another with increased WFS, repeat.
At some point you will not sustain any arc length and the wire will start to stab or stub - and wfs beyond this point is of no use with that wire- because there is not enough current left from the powersource to keep an arc gap.
Simplifying your tooling will reward you with $ and time. Time being the most important.
{ stocking .030 might be cheaper than .024, generally the smaller the wire the more expensive, but the smallest I use is .035 so I am not current on prices. What I mean is if I owned that machine .030 solid, would be my max wire size}