We present the characteristics of a high-energy ultrafast Yb-fiber laser system, based on a Mamyshev regenerator and a subsequently arranged fiber amplifier stage. The Mamyshev regenerator emits pulses at a repetition rate of 10.84 MHz and pulse energies of 47.5 nJ. These pulses are spectrally filtered and amplified in a Yb-doped fiber up to several hundred nanojoule pulse energy which could be temporally dechirped to less than 150 fs autocorrelation duration. We discuss the scaling as well as limiting options related to pulse energies and duration.