I would see if you can get a deviation to the client's specs to use a stub-in (pipe-to-pipe as you refer to it). If you don't have stress problems, and it's not high temperature and/or high pressure, and if the owner permits it, and there are no fatigue issues, a stub-in is perfectly acceptable. Just review the requirements in B31.3 to see if you need a repad. It's done all the time. Yes it has a higher SIF than a WOL; that's why you do the engineering. Downside is a stub-in is dependent on fabrication skill.
For your stress calcs, for a 24 on 60 branch connection I would not use the Code SIF rules and instead use B31J and/or FEA to qualify the connection, then use those SIFs in your pipe stress program.
'The work in getting a suitable "scallop" preparation on a pipe to pipe joint far outweighs any additional costs for a weldolet.' I'm not too sure about that... it would be worth discussing with a good fitter/fabricator. Good pipefitters are fast and can do this all day. You didn't say your location, but if this project is in the Texas Gulf coast then it's no problem; other areas though you might have an issue.