Khelvan

Iphikratean reform is even more un-like the Marian than you suggest, seeing as it’s basically a fantasy.
Epaminondas used hoplites. There is no evidence to suggest he changed any of their gear or their spears. The linothorax had been in use by hoplites since at least the mid-5th century. If by Bulky helmet you mean the iconic Corinthian, it too was largely abandoned before the 4th century for various helmets that addressed its deficiencies. The whole reform ideal rests on vague and late Roman era historians. There is no solid reference in a period historian, pictorial representations, attic orator, or official inscriptions. I don’t deny peltasts and other light infantry was not used more often and more effectively during and after the 4th century, just that the Hoplite changed in any significant way.

I find the Iphikratean hoplite as usually described is also difficult to accept as effective. The longer spear (closer to the Macedonian sarissa than to a hoplite spear) would be unwieldy at best with only one hand. The smaller shield undermines the shield wall effect provided by ‘hoplon’ aspis. Whatever maneuverability was gained with lighter gear seems likely to have been undermined by the complexity of maneuvering a pike with only one hand. Overall, I see an ideal that was neither fish nor fowl, losing the advantages of the hoplite system without the benefits of the Macedonian system.

“Galatian influence of the 290's led to changing the shield to the lighter thureos.”

The thureos may have become popular for light infantry, but I don’t think you can view at part of the kit of troops considered to be ‘Heavy Infantry’
When Philopoemen reformed the Achaean army, he was explicitly rejecting the model of Aratus; light troops, with thureos, and for want of a better word irregular guerrilla tactics. Philipoemon, wanted to win decisive set-piece battles, so he equipped his army with heavy armor and abandoned the light thureos shield for the heavy aspis.