I used a UV system in North TX because of my son's substantial allergy issues. We noticed a difference. We punted on installing a system for a year in TV until I noticed what appeared to be mold or some non-dust contaminate on the air filter on the 1st couple of changes. We put the UV system on and now only see modest dust each change. The higher the MERV rating the more you restrict air flow, increase energy cost, and wear on the blower motor. Here's a site the explains:
MERV 8 vs MERV 11 vs MERV 13 Air Filters: Complete Comparison Guide
– Atomic Filters