Ontario MLS data divide — PropTx (TRREB-led) vs ITSO holdouts; Cornerstone (Waterloo Region) on ITSO with Cotality; single-membership agents must search multiple boards; client-facing duplicate listings + double-counted stats

Claim. Ontario's MLS landscape is fracturing between PropTx (TRREB-led; OMDREB, London, Ottawa, Niagara, KAREA, NAR, NBARA, WITAAR, OnePoint moving over) and ITSO holdouts (Cornerstone Association of REALTORS® for the Waterloo Region context, paying for two full-time Cotality resources; Brantford; BDAR). Single-membership ITSO agents must look up sold comps and run buyer searches across multiple boards; clients see duplicate listings; stats double-count. Practitioner sentiment is sharply divided.

Quote (practitioner — anonymous, DS).

"PropTx is utter garbage in comparison to ITSO. Matrix is far superior."

Source. realestatemagazine.ca (named outlet) + anonymous practitioner comments (DS for the sentiment), accessed 2026-06-21.

Confidence. Industry-consensus for the structural divide; directional-speculative for the comparative-quality framings (anonymous practitioners).

Caveats. "Concerns about a TRREB for-profit MLS monopoly" come from anonymous practitioner comments — directional sentiment, not verified fact. Verify board memberships and system choices against primary board notices before relying on the migration list (OMDREB, London, etc.).

Implication / use. The "fracturing" narrative is real (multi-board cost is real); the comparative-quality narrative is sentiment. Frame the article on the structural divide, not the value judgement.