Hello,
It can steel the sun away from your tea roses. A shrub rose can over shadow other rose bushes. This is the only ill will I can see that a big rose bush could do. Roses like a lot of water the first few years they are in, so be sure with the extra growth from the shrub rose that they get plenty. I would dig and destroy the suckers to keep the area looking "orderly", but that's your call. :0) Happy gardening!!!! Roses are a beautiful addition to any garden, some people are afraid to try them.