Done this? I fear as the BGP process is single threaded and eats a whole cpu of the CCR it may cause problems.
I do do this, albeit limited. My bigger network runs only BGP as it is a core routing setup, in another country we run more an OSPF mesh around about 7 sites linked together by fixed wireless at the moment.
In that country I have 2 BGP routers, one primary supplier one secondary supplier, so I BGP with them, and I then inject only the default route into OSPF from that BGP though, and I do also have a 3rd BGP router peering with an IX but all those routes are pushed into OSPF.
How many routes does the BGP router have? if you are taking full tables then yes changes can and may take some time to reflect in the FIB, but if you are not taking full table then it shouldnt hurt you all that much.