Have had a Hawkeye unit and very easy to use and portable.
Now have Nanocom Evo and again very easy to use and portable.
Can't speak for the Lynx as never used it.
Would all come down to the comparing the spec of each machine, I decided on Nanocom as Hawkeye wouldn't calibrate the SLDS on the Disco II, but apart from that there wasn't much of a difference.
Believe you can also programme 2nd hand key remotes as well.
I have the hawkeye version 6 and honestly cannot praise it enough, so very easy to use and informative, its like land rover diagnostics for dummies, which is probably why I understand it so well, lol.
1. will not synk the speedo, but you dont need such thing cos with that function you can only increase mileage not reduce it whatsoever...hawkeye will disable odometer error warning which is the only thing you need
2. will program used keys like they were new using the excel code generator(from the web) which will give you the long code based on the short one
3. no it will not turn ACE light off, for this you need nanocom or o piece of wire
BUT ... Lynx will do only what hawkeye can cos they are on the same protocol(the original T4 testbook software) and are both 100% reliable when it comes about fault codes, especially from SLABS and ACE ... which nanocom is not... nanocom can turn the ACE light off but it's unreliable to diagnose the system, might give completely wrong fault codes
and if you observed i can speak from my own experience... i'm always using hawkeye for diagnostics