REL R328 & R305 -- are these two REL subwoofers close enough as a match?

I bought a REL 328 as my subwoofer.
I have been been looking for a second one.
Recently, a REL R305 came to my attention.

QUESTION: In a high end music listening system: would this used REL 305 match well enough with my REL 328? Otherwise, I’d like to wait.

The passive radiator is only on the 328. That seems like the biggest difference, but I’m not sure. 
The 328 has the following:
Enclosure Type: Sealed, with Passive Radiator
Driver: 10” Long Throw, steel chassis
Passive: 12" Carbon Fiber VariCone™
Crossover: Variable, 30-120 Hz Stepped
Input Connectors: Neutrik Speakon High-Level input, RCA low level input, .1/LFE RCA input with separate volume control
Amplifier: 350W High Current REL-designed Class D
Dimensions (HWD): 13.5x15.1x15.2"
Weight: 45 lbs

The 305 has the following:
Enclosure Type: Sealed box
Drive Unit: 10" Heavy Duty Long Throw Cast Frame
Crossover: 25Hz to 100Hz
Input Connectors:
Neutrik Speakon - High Level
Phono - LFE Phono - LINE
Amplifier Type: High-Speed, High-Current, Digital Switching Amplifier
Input Impedance
High Level: 150KΩ (Two Channel Unbalanced)
Low Level: 33KΩ (LFE Unbalanced)
Line Level: 10KΩ (Unbalanced)
Input Sensitivity
Low Level: 40dB
High Level: 22dB

Power Output: 300 Watts RMS
Phase: 0 and 180 Degrees
Voltage: 117VAC @ 60Hz
Protection: Over Current, Over Voltage
Fuse: 3.15Amp Slow Blow Small
Dimensions(WHD) 12.5x14.25x13.5
includes feet, controls and grille
Net Weight: 41lbs

This will help you compare the two:
I think that was a serious comment. (Hard to tell sometimes.) If so, do you think that 10 years is too old for a sub? The one I'm considering is 10years old but has been checked out.
Close enough, go for it.

fwiw below is correspondence I had with John Hunter on matching a 328 with a S/3, which are way different than your 328/305 pairing. I’m guessing you wouldn't need to go to those extremes (eg wire each sub mono to each channel), but the general constraints are something to think about (amp & driver differences, phase etc).

As it turned out I skipped the entire experiment and went with dual Syzygy SLF870’s, which for my main room are just fine, waay less hassle and include good-enough room EQ via their built-in dsp and mobile app. I still have a single R328 in another listening room.

John Hunter (REL Acoustics) 2018-Jul-17, 9:46 AM PDT

"it CAN be done but it’s very tricky. If you’ve not done it before you can easily get confused. Room acoustics can be quite different from one side of your system to another and this shows up most in the bass. Add in the quite different voices of S versus R and you could easily get very confused and frustrated. Questions such as "can I expect differences in reproduction between them, to the extent I’d need to compensate with different settings on each?" are extremely intelligent, but minimize the real world experience necessary to have confidence in attempting this.

If you still want to, we’ll guide you through it but know that it’s real work--assuming your current unit is properly set-up, you’ll need to re-wire it to become a monoblock sub dealing only with, say, the left channel.
Then you’ll need to carefully dial-in the right channel new S/3. If one side or another seems predominatnly louder you will want to swap subs because you may need to re-balance the system (room acoustics can swamp the differences between these two subs instantly--the 328 will sound thicker heavier--you may experience it as "louder"--but it’s generally the overshoot you are hearing, the S/3 doesn;t have any of that).
Then dial-in the S/3 (assuming you didn’t need to swap, in which case if you did find swapping was beneficial you’ll need to dial both subs in). Pay zero attention to any setting except phase, which does have to be identical, and simply listen for perfect blend and gain.

Then plug both in and slightly re-tune, fine tune for best performance when using both.

It can be done, just a question of whether you feel comfortable with your own set-up chops."

@usery Thanks for your reply. It looks very tricky for your situation. 

Do you think 10 years is old for a sub? It's priced way under MSRP...

Thanks for thinking about this with me.
I've been enjoying 2 dissimilar REL subs from the "Q" era (at least 10 years ago), a Q108 MKII and a Q150e and they're great together...there's absolutely NO reason not to "mix" well designed subs, and these, bought used a while back, cost about 200 bucks each and work perfectly. Great subs...