A low Recuperation Time is favourable for any weapon. Speed simply reduces the Recuperation Time. The Recuperation Time shown is the total Recuperation Time, after adjusting for Speed and Weapon Expertise.
If you intend to use Hell Spikes, then definately keep the Skull Cap for now. If you want to buy more points in Hell Spikes, take the cap off first so that you don't need as high level to purchase the skill.
And welcome!
