Good advice? Yes and no, depending on how much you want to spend and what you want to get out of it when you're done.
If you just want to get the car back on the road, replace two front shocks with OEM replacement units and be done with it. Yes, this will leave you with new shocks on front and old ones on the rear but some people just want to know the cheapest way to get the car back on the road.
Of course, wtih 125K miles, all of the stock shocks are pretty worn out, so the next step would be to replace all four shocks with OEM replacements to even out the front to rear performance. At this level you can choose between a standard or a Sport shock without too much price difference.
The next step after that is to move up to a coil over shock with new springs. H&R are fine but there are other brands that are just good (Bilstein). Research them to detemine what you want. This is a high end suspension upgrade that will give you adjustability and much greater performance over stock. Just be sure that the ride won't be too harsh for the type of driving that you do.
The price quoted for the H&R suspension seems high when compared to a Bilstein PSS9 setup that can be purchased for ~$2,450. See reference page. Might depend on what other hardware parts are included in the H&R kit.
Just want you to know that there are a LOT of options when it comes to replacing or upgrading your suspension. I am sure that others will add even more suggestions.
References:
Porsche Boxster Suspension - Page 1