Why not start with upgrading from handheld using what you already have before making the leap to the expensive antenna? I was recently right where you are in development but will hold off a little bit.This is what I did. I already had a Elk, and Arrow, 2 FT-857s, a switched AR2 (not mast mounted) preamp. I also picked up a Comet CF-416 duplexer.
I put the Elk on a Alliance U100 and set elevation for 20 degrees, so far just out on sawhorse in the back yard. It works great and does very well for both FM Sats and SSB. Does as well as standing outside but much warmer for the winter and I can safely push a little more power. I run up to 35 W on 2M and 20 W on 70cm but rarely is more than 5 W needed on 2M. I do experience a little crosstalk running V/U but none running U/V. When it gets too annoying I just switch to Xmitting on my 2M turnstile. In my experience, the turnstile is more than enough for the VHF side. Its the 70cm side that really needs all the help it can get.
I can routinely start copying at 5-7 degrees or so, even without being on the roof. Will a beefier antenna do better? Probably, but I was so intrigued by what I had on hand could do that I will run it for a while.
Mike WB1AAT