Generally a first generation of a Gillo product will have “Lux” in the name. This means that it has titanium nitrate coated bushings, wood grips, and other premium fittings. It used to also mean a glossy finish, but now basically all of their products are sandblasted and various degrees of matte.
When the product has been out for a couple years, Gillo often releases an “M” version which is often significantly cheaper. The GT M and GQ M are good examples of this. From a functional standpoint, there are basically no differences. The only noticeable change is that these have a plastic, often 3D printed grip rather than the wood one.
Gillo bows aren’t really designed for barebow specifically, but Gillo was one of the early companies that included barebow specific accessories and attachment points with their recurve risers. This, combined with some happy accidents like the asymmetry on the 27” risers (or, honestly, just the existence of their 27” risers when most other companies didn’t offer them), made them very popular with barebow shooters when barebow began its modern resurgence in popularity around 2014-2016 (which coincided with Gillo’s founding, so they were the hot new thing too).
It’s worth noting that barebow has maintained popularity in Italy due to the popularity of field archery, so they aren’t seen as a niche market by Italian companies (Gillo, Spigarelli, SmartRiser) like it was/is for Hoyt or W&W. What Gillo did differently was to design a riser that didn’t need a separate barebow version to appeal to those archers.
I suspect that when Gillo saw that their barebow sales outstripped their recurve sales, they became a frequent and strong supporter of the barebow class at major events.
The GQ was designed more with recurve archers in mind compared to the G1. Between the current generation GT and GF, I think the GF has some more barebow specific nods like the tunnels for attaching weights, but it also feels great with a stabilizer setup.
Michele obviously does very well with it. Maximiliano did well at Lancaster and Vegas with one last year.
The only drawback I can think of is also a potential positive: most of their risers are comparatively heavy. Not overly so, and the GX series is on the lighter side.