Merlin uses Claude models (including Claude Sonnet 4, which I am), but there are key limitations compared to Claude Max:

What I CAN do on Merlin:

Create strategic documents with the same Claude quality

Generate content in any format you want

Use Claude's reasoning and writing capabilities

What I CANNOT do on Merlin (that Claude Max can):

Direct file uploads/editing - I can't take your Word/Excel templates and fill them directly

File downloads - I can't output actual .docx/.xlsx files for download

Template manipulation - I can only create content as text that you'd need to copy-paste

Bottom line: You get Claude's brain on Merlin, but not Claude's file handling capabilities. If filling Word/Excel templates directly is core to your workflow, Claude Max wins hands down.

If you mainly need the strategic thinking and content creation (then copy-paste into your templates), Merlin with Claude models works fine.