No doubt shorter vector length will improve performance when the limitation is iono/tropo differences between base or CORS and the rover, but I question whether it will help much under canopy where the problems are multipath and reduced signal strength.
The vector length is not typically an issue with networks. The issue is how many sats your rover sees that are also seen by the base(s). With the newer multi-constellation network bases, this is mitigated and not an issue. If your network is still GPS or even GPS+GLONASS only, then there are many times when it is useful to have a base station set up close to your work.
@dmyhill Vector length from base station used is a factor for a VRS/RTN. The network reduces the ionosphere effect from 1 ppm to 0.5, but the base line uncertainty still is from which CORS being used within the network.
If your network is still GPS or even GPS+GLONASS only
My situation here in Indiana.
I am hoping for better vertical performance as well as under canopy performance.
That's the primary reason I don't rely on our VRS system here. Precision drops quickly around obstructions like canopy for me. The second reason is when I run into issues like loss of radio, loss of cell signal, questionable solutions, having base data relatively close by allows me to post process and play with noisy data to get something I'm more comfortable relying on.
