Hello,
IB daily historical backfill for quotetracker is 6 months for futures, 12 months for forex. For stocks I use Yahoo historical backfill which is free with quotetracker and which goes back several years.
I also tested SierraChart with IB backfill, but often had 1 hour of data mssing. Quotetracker is more reliable, as time stamping seems to be compatible.
IB limits backfill , so if I enter too many new futures contracts on rollover date, I have to wait beacuse they cut me off. I can retry after a couple of minutes and continue, wait for the next cut off, retry... in the end backfill will be complete.
Hopefully this answers your question.