For cheaper glass I have been surprisingly happy with my HDMR. I can tell the difference between it and a S&B PMII or something from US Optics, but for the money the HDMR is pretty damn good.
As for FFP - yes it is totally worth it to be able to range at any magnification (or at least to have 1 formula for ranging). As someone else also said go with either mil/mil or moa/moa - doing the conversions to mil/moa or moa/mil is a total pain in the backside.