After searching different sites and reading through numerous threads, I've found a %100 fix for this. I got this from a user over at xda-developers and after testing, I can confirm that this works on my Tilt 2. I thought this had something to do with the custom roms I've been installing, but I think the issue is with a bug in the phone dialer itself because others are having this problem with the stock roms. (*Across all carriers.*) The user mentioned that he installed the cab that I posted below and disabled the HTC Phone Dialer Canvas and everything worked perfect from then on. I've tested this fix plenty of times and can confirm that this fixed my Tilt 2 incoming phone calls issue. The windows phone dialer that you have go use isn't the prettiest, but you never drop an incoming call or have to wait 10/15 seconds for that call to click in. Once you install this cab, click on the icon and then go to: phone>interface>and the slide the option for the phone dialer to off. Click options and apply settings. (*You may receive and error, but that's fine.*) Just soft reset and you're ready to go. Good luck!!
EDIT: This program if for WM 6.5 only. Also, make sure you have .NET CF 3.5 installed.