Hi Ray
I am trying to compile the trinket source for an Attiny84 as it uses V-USB if I used tiny core bootloaders I would need a serial chip for use with the Arduino IDE.
I already have an Attiny84 V-USB project on a custom PCB (below)
I just thought it would be nice to have the option of an Arduino bootloader on it.
The first PCB for the project was actually for an Attiny85 but without a crystal OFC, but enumeration becomes unstable especially between different computers.
With a Attiny2313 or a 84 with a crystal it works on every pc I throw it at whether its USB1,2 or 3 port. I think Adafruit suggest not using USB3 Ports at all with the trinket and I can see why, but unfortunately on allot of modern laptops and later chip sets USB3 is the only option, so it is sometimes pot luck whether it with work or not .
I also noted on some hardware the attiny85 would not even survive a reboot without re-inserting the device.
When i compile the altered source i get an error though. 
Cheers
Koog