100%. I was planning to head to Bournemouth this weekend, but glad I didn't take the chance. Next Saturday XC is being diverted via Salisbury, and some SWRs are going via Havant and Fareham, whilst others are terminating at Winchester. That Sunday, XC will be via Guildford through the North Downs, Portsmouth Direct and West Coastway lines which adds on well over an hour to journey times and seems to often go horribly wrong, and again many SWR services go via Guildford again.
My advice would be to stay well away as well, and practically forget about the promise of buses. From my experience the XC buses seem to be more reliable, compared to SWRs woeful 'service'.