If funds are tight, that is exactly what I would do. Later you could easily add a pair of Studio 60's/100's and move the 20's to the rear. If you don't have a NICE sub (pw-2200 or servo-15 in Paradigm's line but you COULD go with another brand), add that before upgrading the mains. I would...
Studios and don't consider the titans if you have the funds for Studios. There is a huge difference in both HT and Music. I would say I enjoyed moving from the monitor line to the Studio line more with HT because that is my emphasis. Music does sound leagues better as well, but in HT the Studios...