The less expensive model has a saw filter.The more expensive model has a ceramic filter.
It could depend on your location as to which would work better(or be better value for money).
They recently release a 978Mhz UAT version with the saw filter.
This is only useful in the U.S. where 978Mhz UAT is used.
Your stats show a significant increase this week. You will probably be the top feeder(AC and Position reports) in your area next week and be better than top 200 overall feeders in the next few weeks.
I have seen improvements about half of this level from using a later version of dump1090.