The 2010 GO 175 is 91 cm wide, which would make it likely to plane a bit earlier than the 85 cm wide F-155,
but the difference in weight (the 2010 GO 175 weighs 12.93 Kilos) would probably outweigh the 5 cm width
Also, you are using a fairly small sail. What is your weight/height....are you a small person?
Also I believe the Diablo is a fairly dated design so an upgrade to a more modern lighter weight
8.5-9.5 m2 Free race sail like the Severne Overdrive or the Sailworks Retro might get you planning
And, as with all < 10 knots planning scenarios, your pumping skills will be the key to whether you get
to plane or not.
I had some wonderful sessions back in the day when the Formula 155 was brand new.
We found then that putting a 70 cm Fin ( Formula fins had not been invented yet) in it helped
get you planning much earlier. If you have the water depth and clarity to sail a 70 cm fin, you can'
get the F-155 going about 2 knots earlier in the wind spectrum with good rig AND fin pumping
I was reading an old post on this forum from around 2000 where I sailed a F-155 in the Gorge
one week and in San Diego and Long Beach the next week. Great fun, and it was about the
fastest thing on the water at the time.