It appears that what I need is someone to take over a module. The LM PayPal module isn't currently being maintained and the maintainer isn't returning e-mail messages or phone calls.
The E-commerce and Ubercart modules are overkill for what I need, and neither yet has the functionality that LM Paypal's subscription component has. So, I'd like to get out of LM PayPal what it still lacks.
Here's what I wrote to Lee (which I've not gotten a response to):
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My specific needs for the project I'm working on:
1) Sell products using PayPal's subscription process
LM PayPal handles this beautifully, while eCommerce and Ubercart don't have this implemented (yet) at all.
2) Sell products using PayPal's Buy Now process
LM PayPal doesn't have this capability, but eCommerce and Ubercart require a cart and PayPal Express Checkout -- a process that with so much overhead that there's no way I will use it
3) Affiliate tracking and commission payout
This really isn't relevant to LM PayPal, but it's a feature of eCommerce and Ubercart that's not been implemented yet.