I don’t know much about the new Rocket Bass amps, but l've loved my Rumble 500 (210) for over 7 years with nary a discouraging word.
Basically, the R100 and RB112 seem fairly well matched. Both 100 watts into an Eminence 12" speaker, with FX Loop, XLR Line Out, footswitchable dual-controlled Overdrive and special voicings*. Both XLR Outs are affected by the Volume control. Neither can increase power by driving an external cab.
The Rocket costs about 14% more, weighs about 18% more and takes up about 29% more space. The Rumble comes with no internal acoustic lining that some users install to make it sound less "boxy". The Rocket has padded and unpadded inputs, while the Rumble has a Gain control for that and for adjusting drive and Overdrive. The Rocket has Ultra-Hi and Ultra-Lo *voicings, while the Rumble has Vintage, Contour & Bright *voicings. The Rocket has a 3-band B,M,T EQ, while the Rumble has a 4-band B,HM,LM,T EQ.
So, it would appear that, as most people say, it does just come down to whether prefer the Ampeg sound or the Fender sound. And, if you don't know that, ... well, ... that's for
you to find out.
.