An interesting question but I doubt you will be able to get an apples to apples comparison. All Europas are hand built, so all are different. Some have speed kits, some don’t, some have VP props and some don’t (several makes of either prop fitted as well), some are ‘classic’ builds and some are XS. There are about 3 different variants of taildragger Europas, the ‘Swiss mod’, the Miles McCallum Flyer Mod (only 1 of those presently) and in the US the Berube/Grove version. Then there are different engine options from Rotax 80 – 115 hp to Jabiru 80 – 120 hp, some were fitted with Subaru car engine conversions, one was fitted with the Wilksh diesel and one (taildragger I believe) has been fitted with a UL engine.
For what it’s worth, my Mono XS without any speed kit, fixed pitch Warp Drive prop and Rotax 100 hp engine will easily do 120 knots at 5000 rpm, about 135 kts flat out, but I usually cruise at 4800 rpm at 112 kts burning around 15 litres/hr. Mine lives on a 400 m grass strip and climbs at 1000 ft/min at MAUW.
FWIW I know the person who did the flight testing on the Flyer Mod Europa tail dragger, he owns a mono XS and recons the taildragger was bout 3 kts faster. This was some time ago and I don’t know if it was fitted with spats, has a VP prop, eng hp etc. I would suspect that there isn’t much speed difference between mono and taildragger but an obvious weight and speed difference between mono and Tri.
I can also add that Miles is my inspector, he flew the prototype Europa which originally had separate levers for u/carriage and flaps. He lowered the u/carriage in the cruise and saw no speed change!
The Europa owners club is great, further info from here https://www.theeuropaclub.org/