TRI Bike vs. Road Bike

Agree with the above.

Interestingly as well, I spend the vast majority of time on a TT bike and I actually bought a TT bike as my first 'serious' bike even before I bought a road bike, and as such, a have never found the road bike for me to be more 'versatile', as I'm so much more comfortable with the geometry on the TT bike that I prefer for literally everything, including steep climbs which in theory do favor road bikes. 

The best answer for "tri or road bike?" is "both".  You already have a road bike that sounds good enough for what you want it to do.   If you did a lot of recreational road riding, or frequent non-tri-friends group ride, or charity centuries, etc. then upgrading to a better road bike may make sense to you.  But if your intent with your new bike is primarily triathlons and triathlon training, then make your new bike a tri bike.  It's the proper tool for the job.

Another point to consider is "are you willing and able to ride a tri bike in aero position"? The entire purpose of a triathlon bike is to put the relatively huge non-aerodynamic body of the rider into the best possible aerodynamic position which is down on the aerobars in aero position.  For maximum benefit you have to maximize the percentage of time you spend riding in aero position.  That takes starting with the right bike, then getting good fit from someone who knows what he/she is doing, and then riding time in the aero position.

If you don't really intend to ride in aero position, or live somewhere where you can't find the right roads or trails to ride in aero position and thus can't ride that way, then you won't be able to realize the benefit of a tri bike. So if you intend to sit upright on the bike like it's a road bike, then just get a road bike.

BTW, I do agree with the prior poster that switching bikes just before a race is not a great idea.  If your upcoming 70.3 is in late May, you probably do have enough time, but you should consider all the time you'll have to spend thinking about a new bike, shopping for the new bike, fitting the new bike, practicing aero position on the new bike, so on and so forth. That may be fun for you or it may be a big distraction from your training.