I am not sure which model it is, probably we are speaking abou yellow top Marshall? ... I think so, he has also its twin red top Marshall which he flew in past years. I designed those models for his hand some 10 or 12 years ago when I met his daddy, and it is basically MAX (the first one with 45 deg tilted engine
http://www.netax.sk/hexoft/stunt/images/mRim00014.jpg ) modified for inverted ST 60 motor (little modified fatter fuselage). During time he had also modiffication with wing tip with shorter chord redesigned by Alex Schrek for his Extra like model which also uses aerodynamics from Max but different fuselage, but I think it was not best modiffication for such model.
Max itself had several versions:
Max ... orriginal version with Os Max .46 LA with pipe (that why it got name Max)
Max II ... identical to Max, but logartithmic unit on flaps
Max 60 ... clone of Max for Richard and then used by several other 4-2-4 flyers
Max Bee ... my so far the last design cloned from Max II with new improved fuselage
So ... I think we are speaking about older Max 60 called Marschal with TL ST60 ... Richard told us that he decided to fly TL ST60, just for memory of Tom. If I can judge, Richard can fly well both electric and ST60 versions, I do not think that powertrain can have too much influence to flyer ability especially in relatively good conditions in Poland ... IF WORKS WELL ... and all Richards ST60 which I saw in his models worked well. As far as I know he has many of them and he was simply able to select and master those which served well. May be difficuld wind and turbullence will change situation but it was not the case, 3 years ago he decided to use my electric because he saw that it has good reliability especially in hard wind and we know fields here around notoric for strong constant wind :- ))) ... close to Atlantic or high in Alps.