Hi,
The main reason for switching to LSEG was both breadth and depth of coverage. Factset fundamental coverage cutoff is USD 50 mn mcap which leaves a lot of companies out of coverage especially in SME space.
LSEG offers a much more comprehensive coverage.
All Mutual Fund data is sourced from ValueResearch and all stock fundamentals, pricing, corporate action data is sourced from LSEG.
Hope this helps!